Anonymous asked in Science & MathematicsBiology · 1 decade ago

How do bacteria gain access to a cell? Is there some sort of receptor?

I am researching MRSA and am trying it figure out it's life cycle.

2 Answers

  • 1 decade ago
    Favorite Answer

    It's worth mentioning that there are many ways that bacteria in general gain access to a cell. Access (and indeed, host specificity) is generally modulated by the receptors expressed on the surface of the host cell, the phagocytic vs non-phagocytic properties of the host cell (think macrophages, which phagocitize bacteria in order to expose them to concentrated doses of chemical like reactive oxygen species like H2O2), the receptors and adhesins on the surface of the bacterial cell (which are often present in special pathogenicity islands of DNA within the bacterium), and special secretion systems which are also encoded for in these special regions of DNA. Genes found on pathogenicity islands are especially interesting. As is the case with Type Three Secretion Systems (TTSS) which use hypodermic needle-shaped proteins to inject toxins and other host cell effectors to subvert the host's molecular machinery, they are often structurally and functionally conserved across a broad range of bacteria. TTSS are found only in gram negatives and therefore not in MRSA as far as I know, but gram positives have their own secretion systems too. Either way, this conservation indicates a common origin of secretion systems and is strong evidence for horizontal gene flow, often mediated by bacteriophages as well as the better known method of conjugation.

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  • BioLiz
    Lv 7
    1 decade ago

    Staphylococcus aureus (MRSA is a methicillin resistant version of SA) can be pathogenic without invading cells. It can attach to many different surfaces (host cells as well as plastics). This adherence is possible because SA makes so called "adhesins". SA has many adhesins, some of which bind to fibrinogen, others to fibronectin, collagen, elastin, as well as a broad spectrum adhesin. This is one sticky bacterium!

    However, it is capable of invasion into host cells as well. SA makes proteins that bind fibronectin. Fibronectin in turn can bind to host integrins, and thus SA will be taken up by the host cell (invasion).

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