Bacterial Pathogenesis

University of California, Berkeley

SPRING 2007

(MCB 103, PLANT BIO 103, PB HLTH 102, PB HLTH 262)

Daniel A. Portnoy, Ph.D.

Matthew Welch, Ph.D.

Gregory Barton, Ph.D.

GLOSSARY

A-B toxin

• B portion of toxin responsible for binding to target cell is separate from A portion that mediates enzymatic activity (Lecture: Toxins/Diphtheria)

ActA

• Surface protein of Listeria monocytogenes responsible for actin nucleation by stimulating the host Arp2/3 complex. (Lecture: Listeria monocytogenes II)

Actin

• A major protein component of host cell cytoskeleton; one of the most abundant proteins in eukaryotic cells. It comprises from 1-20% of the total cell protein. Comprised of monomeric G-actin and polmerimeric F-actin. Actin polymerization is necessary for cell motility and phagocytosis (Lecture: The Actin Cytoskeleton)

Adaptive immunity

• The ability of an organism to develop a specific increased resistance to a pathogen with associate memory. Mediate by T and B lymphocyes. (Lecture: Acquired Immunity)

Adenylate cyclase

• Protein toxin produced and secreted by Bordetella pertussis and B. bronchiseptica; catalyzes synthesis of cAMP and is host calmodulin-dependent. Consist of two domains, a hemolysin domain that mediates translocation and the enzyme adenylate cyclase. (Lecture: Bordetella pertussis and B. bronchiseptica)

Aminoglycoside

• Family of antibiotics that bind to the 30S ribosomal subunit and inhibit protein synthesis (examples streptomycin, gentamicin) (Lecture: Antibiotics and Antibiotic Resistance)

Ampicillin (amp)

• In class of beta-lactam antibiotics; inhibits transpeptidation step in peptidoglycan synthesis (Lecture: Antibiotics and Antibiotic Resistance)

Antibody

• A protein present in serum or other body fluid that combines specifically with antigen; an immunoglobulin (Lecture: Acquired Immunity)

Antigen

•  A substance that interacts with a T cell receptor or an immunoglobulin (Lecture: Acquired Immunity)

Arp 2/3 Complex

• Conserved actin nucleating factor in eucaryotic cells. It consists of a tight association of seven polypeptide subunits - two actin related proteins (in the Arp2 and Arp3 subfamilies) together with five other subunits. Combines with the L. monocytogenes ActA protein to from an actin nucleus (Lecture: The Actin Cytoskeleton)

Autolysins

• Enzymes produced by bacteria which digest peptidoglycan and can cause lysis of bacteria (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation I)

Auxotroph

• A microorganism that has lost the ability to synthesize an essential nutrient (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation II)

Bactericidal

• Substance usually an antibiotic that kills bacteria (Lecture: Antibiotics and Antibiotic Resistance)

Bacteriostatic

• Substance that inhibits growth of bacteria but does not kill them (Lecture: Antibiotics and Antibiotic Resistance)

Bafilomycin

• A drug that prevents acidification of the endosomes and phagosomes by blocking the vacuolar proton pump and thereby prevents acidification. Block the action of DT (Lecture: Toxins/Diphtheria)

Beta-lactam antibiotics

• Antibiotics that contain a beta-lactam ring and act via inhibition of peptidoglycan synthesis (includes penicillins, cephalosporins, carbapenems, and monobactams) (Lecture: Antibiotics and Antibiotic Resistance)

Beta-lactamase

• Enzyme that cleaves the beta-lactam ring of beta-lactam antibiotics and thus inactivates them (Lecture: Antibiotics and Antibiotic Resistance)

"Big Three"

• Tuberculosis, HIV, Malaria (Lecture: Overview of Bacterial Pathogenesis)

Biofilm

• Multilayer bacterial populations embedded in a polysaccharide matrix that is attached to some surface (plastic, mucosal membrane) (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation II)

bvgA,S

• Bordetella virulence genes; encode a two-component regulatory system that co-ordinately activates many virulence genes (VAGS) and represses other genes like those involved in motility (VRGS). (Lecture: Bordetella pertussis and B. bronchiseptica)

Calcium dependence

• An unusual requirement for calcium seen in the pathogenic Yersinia species. May reflect the capacity of Y. pestis to recognize the intracellular environment, because extracellular calcium is 2.5 mM and intracellular calcium is micromolar (Lecture: Yersinae II)

Chemokines

• Related family of proteins produced by many mammalian cell types that mediate chemotaxis and organize activities of cells of specfic and non-specific defenses (Lecture: Innate Immunity and Inflammation II)

Chemotaxis

• Movement of cell toward a particular substance; movement away from a repellant (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation II)

Chloramphenicol (cm)

• Antibiotic that inhibits protein synthesis by acting on the ribosome 50S subunit(Lecture: Antibiotics and Antibiotic Resistance)

Cholera toxin (CT)

• A-B exotoxin produced by Vibrio cholerae which ADP-ribosylates a Gs protein thus locking it in the GTP-bound active state. Results in enhanced adenylate cyclase activity. (Lecture: Vibrio cholerae)

Cholesterol-dependent cytolysins (CDCs)

• Toxins secreted by some gram-positive bacteria that bind cholesterol, oligomerize and form pores (Lecture: Toxins/Diphtheria)

Competence

• Capacity to take up DNA and become genetically transformed (Lecture: Bacterial Molecular Genetics I)

Complement receptors (CRs)

• Cell-surface proteins on macrophages that recognize and bind complement C3b bound to an antigen such as a pathogen; CRs on phagocytes allow them to identify pathogens coated with complement proteins for uptake. (Lecture: Innate Immunity and Inflammation I)

Complement system

• A group of plasma proteins that mediate the inflammatory response when activated; complement has three functions: 1) opsonic (enhances phagocytosis by attaching complement component C3b to bacteria), 2) chemotactic and 3) lytic (disrupts membrane and releases contents of a bacterial or host cell) (Lecture: Innate Immunity and Inflammation I)

Conjugation

• Transfer of genes from one procaryotic cell to another by a machanism involving cell-to-cell contact (Lecture: Bacterial Molecular Genetics I)

Corynebacterium diphtheriae

• Gram-positive, non-spore-forming, nonmotile, aerobic rod with club-shaped appearance; causative agent of diphtheria (Lecture: Toxins/Diphtheria)

Cytochalasin D

• Fungal alkyloid that binds to the + end of actin filaments and prevents elongation. Cytochalasin is membrane permeant, and its addition to living cells blocks actin polymerization and phagocytosis(Lecture: The Actin Cytoskeleton)

Cytokines

• Signaling proteins produced by some mammalian cells in response to stimuli; mediators of inflammation, toxic shock (Lecture: Innate Immunity and Inflammation II)

Diphtheria toxin

• A-B toxin secreted by C. diphtheriae that blocks human cell protein synthesis by ADP ribosolation of EF-2 (Lecture: Toxins/Diphtheria)

Effector cell

• Combats infection by producing antibodies, cytokines, and chemokines, or by killing of infected cells (Lecture: Acquired Immunity)

Electroporation

• The use of an electronic pulse to enable cells to take up DNA (Lecture: Bacterial Molecular Genetics I)

Erythromycin (em)

• Macrolide antibiotic that targets the 50S ribosomal subunit; can be cidal or static (Lecture: Antibiotics and Antibiotic Resistance)

Extravasation (also transmigration)

• Movement of PMNs across blood vessel wall into tissues (Lecture: Innate Immunity and Inflammation II)

Facultative anaerobe

• An organism that can use either fermentation or respiration to obtain energy, depending on whether or not oxygen is present (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation II)

Fc Receptors (FcR)

• Protein receptors for the Fc portion of Immunoglobulin present on macrophages and neutrophils. Mediate phagocytosis of Antibody coated particles. Many different FcRs with specificity for different Immunoglobulin isotypes. Molecular link between the innate and acquired immune system (Lecture: Innate Immunity and Inflammation I)

Formylmethionine

• In bacterial protein synthesis, the initiation codon, AUG, specifies formylmethione (F-met). (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation III)

General secretory pathway (GSP or Sec-dependent pathway)

• Pathway through which many proteins are exported from the cytoplasm to the periplasm; requires signal sequence on protein being secreted. SecA is an essential component of the GSP. (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation II)

Gentamicin (gm)

• Aminoglycoside antibiotic that binds to the ribosomal 30s subunit; is bacteriocidal. Used in tissue culture assays to kill extracellular bacteria (Lecture: Antibiotics and Antibiotic Resistance)

Gram-negative bacteria

• Bacteria containing an outer membrane and LPS or LOS. In this course we will discuss the following gram-negative bacteria: Vibrio cholerae, the Bordetellae, Neisseriae, Yersiniae, Salmonellae, Chlamydiae, and Pseudomonas. These bacteria lose the crystal violet color after decolorizing by alcohol; they stain pink after treatment with safranin (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation I)

Gram-positive bacteria

• The cell wall of gram-positive bacteria, consisting of a thick layer of peptidoglycan and teichoic acids. In the course we will discuss the following low G+C gram-positive bacteria: Sreptococci and Staphylococci, and Liseriae; we will discuss the followoing high G+C gram-positive bacteria: Corynebacterium diphtheriae and Mycobacterium tuberculosis. (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation I)

Incompatibility

• Plasmids that cannot co-exist are incompatible and belong to the same compatibility group (Lecture: Bacterial Molecular Genetics I)

Inflammation

• The local accumulation of fluid, plasma proteins, and white blood cells that is initiated by physical injury, infection, or a local immune response (Lecture: Innate Immunity and Inflammation II)

Innate immunity

• In an evolutionary sense, this is the ancestral immunity present in normal individuals at all times and does not increase with repeated exposure to a given pathogen. Responsible for clearance of most infections (Lecture: Acquired Immunity)

Invasin (Inv)

• Approximately 100-kDa outer membrane protein from Yersinia enterocolitica and Y. pseudotuberculosis that is sufficient to confer the invasive phenotype upon E. coli K12. It 's receptor is an integrin (Lecture: Yersiniae I)

Invasion assay

• Assay to quantitiate the number of interalized bacteria using gentamicin resistant cfus and expressed as the percentage of bacteria internalized. (Lecture: Yersiniae I)

In vivo expression technology (IVET)

• Means of identifying bacterial genes that are expressed only when the bacteria are in the host (Lecture: Experimental Approaches to Pathogenesis: The Tools of the Trade)

Koch's Postulates

• A set of postulates that must be met to prove that a particular bacterial pathogen causes a particular disease (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation II)

Koch's Postulates, Molecular Version

• 1. The phenotype or property under investigation should be associated with pathogenic members of a genus or pathogenic strains of a species.

  2. Specific inactivation of the gene(s) associated with the suspected virulence trait should lead to a measurable loss in virulence in a appropriate model system. In-frame deletions or point mutations are best.

  3. Complementation of the mutation either on a plasmid or by allelic replacement of the mutated gene should lead to restoration of pathogenicity.

  (Lecture: Experimental Approaches to Pathogenesis: The Tools of the Trade)

Lipid A

• Toxic portion of LPS; embedded in the outer membrane (OM); covalently linked to O antigen which protrudes from bacterial surface; essential for viability; Is endotoxin! (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation I)

Lipo-oligosaccharide (LOS):

• Component of outer membrane of some gram-negative bacteria; similar to LPS in structure but with a shorter O antigen (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation I)

Lipopolysaccharide (LPS)

• Component of the gram-negative outer membrane (OM); consists of Lipid A (the toxic portion), a core made up of a series of sugars, and the O antigen, a long carbohydrate chain; forms the outer leaflet of the gram-negative outer membrane (OM). (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation I)

Listeria monocytogenes

• Low G+C gram-positive, facultative anaerobe; temperature-dependent motility; unusually broad ecological niche; causative agent of listeriosis; model pathogen for the study of cell-mediated immunity (Lecture: Listeria monocytogenes I)

Listeriolysin O

• Essential L. monocytogenes determinant of pathogensis largely responsible for mediating escape from a host cell vacuole; member of Cholesterol-Dependent Cytolysins (CDCs); binds cholesterol and oligomerizes into oligomers; related to streptolysin O, perfringolysin O (PFO), and pneumolysin, all of which are secreted by extracellular pathogens (Lecture: Listeria monocytogenes I)

Lymphocyte

• White blood cell involved in the immune response; includes B cells and T cells (Lecture: Acquired Immunity)

M-Protein and M-like proteins

• Surface-exposed protein(s) on Streptococcus pyogenes that is the primary target of IgG; Have classic LPXTG motif and are thus anchored to the peptidoglycan; play antiphagocytic role (Lecture: The Gram-Positive Cocci: Streptococcus and Staphylococcus)

MacConkey Agar

• A plating medium for the detection of gram-negative bacteria. It is selective for the gram-negative bacteria, because it contains bile salts and crystal violet, and differentiates between them on the basis of lactose fermentation; pH indicator is neutral red. (Lecture: Experimental Approaches to Pathogenesis: The Tools of the Trade)

Macrophages

• Large tissue mononuclear cell having phagocytic and antigen-processing activity; develops from monocyte. Often act as hosts to intracellular pathogens. Upon activation, can kill pathogens. (Lecture: Innate Immunity and Inflammation I)

MHC molecule - class 1, class 2

• MHC-1: Major Histocompatibilty Complex (MHC) type that, when bound to an epitope and displayed on the surface of a host cell, triggers activation and proliferation of cytotoxic T cells; found of most cells in body; associated with display of epitopes of intracellular pathogens (Lecture: Acquired Immunity, 2/14/02)
• MHC-2: MHC type that, when complexed with an epitope and displayed on the surface of an antigen-presenting cell leads to activation and proliferation of T-helper cells; found on only a few cell types (e.g., APCs) (Lecture: Acquired Immunity)

Naladixic acid (nal)

• Quinolone antibiotic that inhibits DNA gyrase and blocks bacterial replication (Lecture: Antibiotics and Antibiotic Resistance)

Neutralization

• Antibodies bind to surface of microbe and block function of pathogen adhesions or toxins (Lecture: Acquired Immunity)

Neutrophils

• Polymorphonuclear leukocyte or PMN. Represent 50% of the white blood cells. Are bacteriocidal and the first cells to migrate to sites of inflammation (Lecture: Innate Immunity and Inflammation I)

Operon

• Transcriptional unit consisting of structural genes controlled by an adjacent operator (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation III)

Opportunistic pathogen

• A microorganism that does not cause disease in a healthy host, but only in individuals whose normal defense mechanisms have been compromised (e.g., burn patients, recipients of organ transplants receiving immunsuppresants, individuals with AIDS, pregant women) (Lecture: Overview of Bacterial Pathogenesis)

Opsonization

• Alteration of a particle (pathogen) with antibody or complement that facilitates their uptake through receptors on a phagocytic cell (Lecture: Acquired Immunity)

Pathogen

• A microorganism capable of producing pathology (disease) (Lecture: Overview of Bacterial Pathogenesis)

Pathogenicity islands

• Refers to large chromosomal regions in pathogenic bacteria that encode virulence genes (Lecture: Bacterial Molecular Genetics II)

Peptidoglycan

• Polysaccharide backbone with peptide cross-links that covers surface of cytoplasmic membrane and gives bacteria their shape (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation I)

Periplasm

• Region between inner membrane (IM) and outer membrane (OM) (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation I)

Pertussis Toxin (PT)

• A-B exotoxin produced by Bordetella pertussis that ADP-ribosylates a Gi protein thus locking it in the GDP-bound inactive state. Results in enhanced adenylate cyclase activity. (Lecture: Bordetella pertussis and B. bronchiseptica)

Phage conversion

• A form of specialized transduction wherein a bacteriophage introduces a heritable change (i.e., diphtheria toxin) (Lecture: Bacterial Molecular Genetics I)

Plasmid

• An extrachromosomal genetic element that is not essential for growth, but confers a selective advantage in certain environments(Lecture: Bacterial Molecular Genetics I)

Pneumolysin (PLO)

• Member of the CDC famnily of pore-forming cytolysins produced by Streptococcus pneumoniae; Unique in that it lacks a signal peptide; related to SLO and listeriolysin (Lecture: The Gram-Positive Cocci: Streptococcus and Staphylococcus)

Polarity

• Occurs when a mutation in an operon affects genes downstream in the operon. Note that transposons cause polar mutations. (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation III)

Promoter

• Site on DNA where RNA polymerase binds and initiates transcription (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation III)

Protein A

• Surface-exposed protein of Staphylococcus aureus with LPXTG motif that binds the Fc portion of antibodies (Lecture: The Gram-Positive Cocci: Streptococcus and Staphylococcus)

Prototroph

• The parent from which an auxotrophic mutant is derived (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation II)

Quorum sensing system

• Recognizes bacterial signal (autoinducer), thus sensing density of bacteria; can control activity of either repressor or activator (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation III)

Reactive Nitrogen Intermediates (R.N.I.)

• Forms of nitrogen such as nitric acid that kill bacteria; produced in macrophages (Lecture: Innate Immunity and Inflammation II)

Reactive Oxygen Intermediates (R.O.I.)

• Upon phagocytosis, NADPH oxidase is activated, which reduces oxygen to superoxide; superoxide dismutase converts superoxide to hydrogen peroxide; together, these are referred to as R.O.I. These products are toxic to bacteria (Lecture: Innate Immunity and Inflammation II)

recA

• A conserved gene in all procaryotes, it is essential for recombination (Lecture: Bacterial Molecular Genetics I)

Regulon

• Genes at different locations having promoter-operator regions that all recognize the same regulator protein(s) (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation III)

Reporter gene

• Structural gene encoding easily assayable enzyme that is fused to a heterologous promoter region by cloning or other genetic means; used in transcriptional fusions or translational fusions (Lecture: Bacterial Molecular Genetics II)

Respiratory burst (also oxidative burst)

• Production of reactive oxygen intermediates (R.O.I.) by phagocytes (Lecture: Innate Immunity and Inflammation II)

Rho

• Mammalian small GTP-binding protein that regulates actin polymerization targeted by toxins A and B of Clostridium difficile. Active in GTP bound state and inactive in GDP-bound state. Microinjection of cells with constitutively active Rho causes the formation of stress fibers and focal adhesions. (Lecture: The Actin Cytoskeleton)

Rifampin (rif)

• Antibiotic that binds subunit of bacterial RNA polymerase and blocks transcription; is bacteriostatic (Lecture: Antibiotics and Antibiotic Resistance)

Rough mutants

• Identified by colonial morphology. In gram negative bacteria, missing part of LPS. ranging from O-side chain to part of the core. (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation I)

SecA protein

• An ATPase that mediates insertion of the preprotein into the secretion complex and drives the reaction. (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation II)

Selective toxicity

• Relative toxicity of antibiotic to bacteria compared to the host. (Lecture: Antibiotics and Antibiotic Resistance)

Serotype

• Classification of bacterial strains within a sero-group based on a surface antigen In Escherichia coli, there are three components of serotype, the O, H, and K antigens (O for O-side chain of the LPS; H for the flagella antigen, and K for capsule. (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation I)

Staphylococcus aureus

• Gram-positive cocci, non-motile, facultative anaerobe, grows in clumps like grapes; causative agent of staph food poisoning, skin infections and toxic shock syndrome (Lecture: The Gram-Positive Cocci: Streptococcus and Staphylococcus)

Streptococcus pyogenes (S. pyogenes or group A strept, GAS, or beta hemolytic strept)

• Gram-positive cocci, grows in chains, facultative anaerobe, obligate human niche; causative agent of streptococal pharyngitis (strept throat), rheumatic fever, and toxic shock-like syndrome (Lecture: The Gram-Positive Cocci: Streptococcus and Staphylococcus)

Streptococcus pneumoniae (diplococcus)

• Gram-positive diplococcus, non-motile, facultative anaerobe; causative agent of pneumonia and ear infections. (Lecture: The Gram-Positive Cocci: Streptococcus and Staphylococcus)

Streptolysin O (SLO)

• A member of the CDC family of pore-forming cytolysins produced by Streptococcus pyogenes; related to pneumolysin and listeriolysin O (Lecture: The Gram-Positive Cocci: Streptococcus and Staphylococcus)

Streptomycin (sm)

• Aminoglycoside antibiotic, binds 30S subunit of bacterial ribosome and causes ribosome misreading. (Lecture: Antibiotics and Antibiotic Resistance)

Stringent response system

• Bacterial response to starvation for amino acids by synthesizing ppGpp which mediates appropriate gene expression such as repression of stable RNAs. (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation III)

T-cell receptor

• Protein complex on surface of T cells; recognizes a specific epitope presented on MHC by an antigen-presenting cell (Lecture: Acquired Immunity)

Terminator

• The sequence of DNA at which the RNA polymerase iis released (i.e., stops transcibing) (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation III)

Tetracycline (tet)

•  Antibiotic that binds 30S subunit of bacterial ribosome; is bacteriostatic (Lecture: Antibiotics and Antibiotic Resistance)

Toxin coregulated Pili (TCP)

• Bundle forming pilus of Vibrio cholerae whose expression is co-ordinately regulated with cholera toxin. Receptor for cholera toxin bacteriophage (Lecture: Vibrio cholerae)

Tumor necrosis factor (TNF)

• Cytokine produced by monocytes and macrophages in response to LPS (Lecture: Innate Immunity and Inflammation II)

TnphoA

• Transposon with a gene at one end encoding alkaline phosphatase but without its signal sequence; an example of a system for identifying mutants using translational fusions (Lecture: Bacterial Molecular Genetics II)

Toll-like receptors

• Evolutionarily conserved family of receptors first described in Drosophila which mediate anti-microbial recognition and host defense in Drosophilia and in mammals (Lecture: Innate Immunity and Inflammation I)

Toll-like receptor 4

• Receptor that is specific to Lipid A of LPS (Lecture: Innate Immunity and Inflammation II)

Transcription unit

• Region from the promoter to the terminator (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation III)

Transcriptional fusion

• Hybrid gene with promoter-operator of one gene fused to a promoterless structural gene encoding an assayable enzyme (Lecture: Bacterial Molecular Genetics II)

Transduction

• Transfer of host genes from one cell to another by a bacteriophage (Lecture: Bacterial Molecular Genetics I)

Transformation

• Transfer of genetic information via free DNA. (Lecture: Bacterial Molecular Genetics I)

Translational fusion

• In-frame fusions between two proteins such that the promoter, ribosome binding site, start codon, and some or all of the coding sequence are fused in-frame with another protein (Lecture: Bacterial Molecular Genetics II)

Transposon

• A jumping gene; segment of DNA containing insertion sequences plus one or more genes not related to transposition (Lecture: Bacterial Molecular Genetics II)

Two-component regulatory systems

• One protein is a membrane sensor kinase that senses the signal and catalyzes autophosphorylation at a histidine residue, then phosphorylates second protein, the response regulator, at an aspartic acid, to produce the form that activates transcription (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation III)

Type III secretion-independent pathway (contact-dependent secretion pathway)

• Secretion pathway used by a variety of gram-negative pathogens; toxic proteins are injected directly from the cytoplasm of the bacterium into the cytoplasm of the host cell. Is a multiprotein complex with homology to flagella (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation II)

Type IV pili (TFP)

• pili in which pilin subunit is processed so that the first amino acid in mature protein is N-methylphenylalanine. Responsible for twitching motility. (Lecture: The Bacterial Cell: Structure, Function, Growth, and Gene Regulation II)

Vibrio cholerae

• Gram-negative, facultative anaerobe, comma-shaped highly motile with single polar flagella; causative agent of cholera, a water-borne illness transmitted as a result of ingesting contaminated food or water (Lecture: Vibrio cholerae)

Virulence

• Ability of an organism to cause disease (Lecture: Overview of Bacterial Pathogenesis)

WASP

• Mutated in the human immune deficiency disease Wiscott-Aldrich syndrome. Function in actin nucleation by stimulating the activity of the Arp2/3 complex. (Lecture: The Actin Cytoskeleton)

Yersiniae

• Gram-negative, facultative anaerobic bacteria in the family of Enterobacteriaceae; Yersinia pestis is the causative agent of plague; Yersinia enterocolitica and Yersinia pseudotuberculosis cause enteric disease due to contaminated food or water. (Lecture: Yersiniae I)

YopE

• Type III secretion effector in Yersiniae that acts in concert with YopH to block phagocytosis; GTPase-activating protein (GAP) acting on Rho-family members. (Lecture: Yersiniae II)

YopH

• Type III secretion effector in Yersiniae is a tyrosine phosphotase (Lecture: Yersiniae II)

Some of the above definitions have been taken from the glossaries of the following course texts:

• Salyers, Abigail A and Whitt, Dixie D. Bacterial Pathogenesis, A Molecular Approach, 2nd edition. ASM Press, 2002.
• Madigan, Michael T, Martinko, John T. and Parker, Jack. Brock Biology of Microorganisms, 9th edition. Prentice-Hall, 2000.