Microbial Warfare Flashcards
how does streptomyces protect itself from the antibiotics it secretes
-encode some mechanism of resistance
antibiotic production of streptomyces
-highly regulated due to evolution and resistance
-often produced during starvation - produced to inhibit growth of competitors to allow them to complete sporulation process
-arms race between ways to create Ab (streptomyces) and survive (victims)
type VI secretion systems
-essentially a synringe/needle to inject toxic proteins (effectors) into competing bacteria
-requires contact-only useful for close range
-not all species encode T6SS - not part of the core genome
-in rare cases T6SS is used to target eukaryotic host
how does the attacking cell protect against self-intoxication
-immediately downstream of the T6SS effector an immunity protein is encoded to protect against self-intoxication
what does an effector of T6SS do
-target and often degrade cellular structures such as cell wall, membranes and DNA
bacteriocins
-protein toxins produced/secreted by certain bacteria
-similar to antibiotics and T6SS
-strain to strain variation in bacteriocin produces, some produce non, others produce multible
-immunity proteins protect producer
bacteriocin structure and target
–variability in structure/function/mechanism
-target cell wall, membrane and DNA
-often have domains that enable the proteins to cross outer and cytoplasmic membrane to access target
-some commerical use in food preservation
-some bactericins are chemically modified proteins
Nisin
-used in food preservation
-targets cell wall synthetis sand is active against broad spectrum gram positive bacteria
bacterial predation and competence
-sometimes T6SS and or bacteriocins are coordinated with competance
-hypothesis: times are tough and you dont have the resources to deal with it? kill your neighbour, steal their DNA ..Maybe they have genes that can help
Killer toxins
-eukaryotic microbes employ protein toxins analogous to bacteriocins
-killer yeasts produce toxins that kill other yeasts
-often encoded by viruses or plasmids
-killers encode immunity to toxin
-killer strains impact fermentation industries
two parts of protein toxin of killer toxins
-remember this is eukaryotic
-two parts: one part exhbits toxicity, other part triggers uptake into target cells
bacteria as food for eukaryotes
-free living amoeba for example (eukaryotic microbes) consume and digest bacteria as primary food and energy source
-use psuedopods to engulf bacteria
-phagocytosed into a vacuole and fuses with lysosome
-in lysosome, bacteria are klled and digested by low pH and digestive enzyme
legionella pneumphila
-gram neg causing pneumonia
-natural reservoir is aquatic amoeba - manupulating the biology to surive here
-after engulfment by ameoba they avoid fusiion with lysomes and create legionella containing vacuole
-these mechanisms also allow legionella to surivei in human cells
-amoeba taight legionella how to surivie within out immune cells
how does legionella create LCV
-uses type 4 secretion system to inject specific effector proteins into amoeba and other eukaryotics
-effector proteins maipulate host cell biology in several different ways to enable legionella to establish a replciation niche (LCV) within these cells
