Posted by: Dan | July 27, 2007

Bacterial Cytoskeleton


[Figure 1 from Shih and Rothfield (2006); click on image to enlarge]

Recently, Alex had asked for a mention of the bacterial cytoskeleton, which does deserve mention. As Shih and Rothfield describe, the amino acid sequences of eukaryotic and bacterial cytoskeletal monomers bear minimal resemblance to one another. Their 3-dimensional structures, however, bear striking resemblances – in particular, compare Actin and beta-Tubulin with ParM and BtubA, respectively.

Similarly, these structural homologs share important properties, such as the capacity to self-assemble into filamentous polymers in vitro in the presences of ATP or GTP, and their ability to organize into ordered long-range structures within the cell. Also, they serve comparable cellular functions, including chromosome segregation, cytokinesis, regulation of cell shape, and establishment of cell polarity.

It’s also worth noting, from the viewpoint of the evolutionary continuum between prokaryotes and eukaryotes, that these few proteins are not the whole set of cytoskeletal proteins. They’re just the most studied, and as Shih and Rothfield (2006) point out, there are plenty of others, indicating a range of protein structures that are possible.

  • Shih YL, Rothfield L. The bacterial cytoskeleton. Microbiol Mol Biol Rev. 2006 Sep;70(3):729-54.

Responses

  1. On Proto-Sexuality
    (an experiment in Double Dactyly)

    . . . efficient sexual reproduction requires the packaging of genetic material into discrete units (chromosomes). Thus, in eukaryotes, sex cells have half the chromosomes of normal body cells. When two sex cells join to produce an offspring, the original amount of genetic material is restored. Prokaryotic sex, on the other hand, is infrequent and inefficient. (It is unidirectional, involving the transfer of a few genes from a donor cell to a recipient.) Stephan J. Gould, Ever Since Darwin, 1977, 116.

    Unidirectional
    Prokaryotic sex
    Happens chiefly by chance
    And precludes foreplay.

    Stephan J. Gould claims
    That eukaryotic sex
    Efficiently, frequently
    Evolves us today.

    –Mark Worden

  2. Lo que hoy nos parece correcto puede que mañana no lo sea. El conocimiento biológico es abrumador. Los textos de estuduio suelen afirmar que una gran diferencia entre las células eucariontes y procariontes es la presencia de citoesqueleto por parte de las primeras. Esto esta cambiando.

    Una cosa no ha cambiado. La conjugación bacteriana no es un mecanismo sexuado, es solo un proceso de recombinación genetica, dado que no da como resultado multiplicación celular. Es solo recombinación genetica intercelular.It is only unidirectional, involving the transfer of genetic information from a donor cell to a recipient.

    M. Hidalgo O. PhD


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