Affiliation:
1. Instituto de Investigaciones Biomédicas
2. Centro de Ciencias Genómicas
3. Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México D.F. 04510, México
Abstract
ABSTRACT
Bacteria swim in liquid environments by means of a complex rotating structure known as the flagellum. Approximately 40 proteins are required for the assembly and functionality of this structure.
Rhodobacter sphaeroides
has two flagellar systems. One of these systems has been shown to be functional and is required for the synthesis of the well-characterized single subpolar flagellum, while the other was found only after the genome sequence of this bacterium was completed. In this work we found that the second flagellar system of
R. sphaeroides
can be expressed and produces a functional flagellum. In many bacteria with two flagellar systems, one is required for swimming, while the other allows movement in denser environments by producing a large number of flagella over the entire cell surface. In contrast, the second flagellar system of
R. sphaeroides
produces polar flagella that are required for swimming. Expression of the second set of flagellar genes seems to be positively regulated under anaerobic growth conditions. Phylogenic analysis suggests that the flagellar system that was initially characterized was in fact acquired by horizontal transfer from a γ-proteobacterium, while the second flagellar system contains the native genes. Interestingly, other α-proteobacteria closely related to
R. sphaeroides
have also acquired a set of flagellar genes similar to the set found in
R. sphaeroides
, suggesting that a common ancestor received this gene cluster.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
59 articles.
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