POSTERS - BLAST X - University of Utah
POSTERS - BLAST X - University of Utah
POSTERS - BLAST X - University of Utah
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<strong>BLAST</strong> X Thurs. Morning Session<br />
RHODOBACTER SPHAEROIDES, A BACTERIUM WITH TWO FLAGELLAR SYSTEMS AND<br />
MULTIPLE CHEMOTAXIS GENE HOMOLOGS<br />
Ana Martínez del Campo 1 , Sebastian Poggio 2 , Teresa Ballado 1 , Aurora Osorio 2 , Javier de la<br />
Mora 1 , Laura Camarena 2 and Georges Dreyfus 1<br />
Instituto de Fisiología Celular 1 , Instituto de Investigaciones Biomédicas 2 , Universidad Nacional<br />
Autónoma de México, 04510 México DF, México.<br />
Rhodobacter sphaeroides has two flagellar systems (fla1 and fla2). One <strong>of</strong> these<br />
systems has been shown to be functional and is required for the synthesis <strong>of</strong> the wellcharacterized<br />
single subpolar flagellum (fla1), while the other was found only after the genome<br />
sequence <strong>of</strong> this bacterium was completed (fla2). In this work we found that the second flagellar<br />
system <strong>of</strong> R. sphaeroides can be expressed and encodes a functional flagellum. This second<br />
flagellar system produces polar flagella that are required for swimming. Phylogenic analysis<br />
suggests that the flagellar system that was initially characterized, was in fact, acquired by<br />
horizontal transfer from a γ-proteobacterium, while the second flagellar system contains the<br />
native genes.<br />
In addition to having two flagellar systems, this photosynthetic bacterium posses several<br />
reiterated chemotactic genes (2 cheB, 3 cheR, 4 cheA and cheW and 6 cheY), which are<br />
encoded in three operons (cheOp1, cheOp2 and cheOp3). In spite <strong>of</strong> this, only some <strong>of</strong> the<br />
gene copies are required when the cell is swimming with the fla1 flagellum. The presence <strong>of</strong> a<br />
second functional flagellum (fla2) suggests that some <strong>of</strong> these genes could be involved in its<br />
tactic control. To test this hypothesis we proceeded to individually mutate each cheY gene. We<br />
show evidence that CheY1, CheY2 and CheY5 control de chemotactic behavior mediated by<br />
fla2 flagella. Additionally, we identified that open reading frame RSP6099 encodes the fla2 FliM<br />
protein. Furthermore CheY1, CheY2 and CheY5 are located within cheOp1, which is not<br />
essential for chemotaxis mediated by the fla1 system. This raises the question: What is the role<br />
<strong>of</strong> cheOp1?<br />
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