Genes for the Cytoskeletal Protein Tubulin in the Bacterial Genus Prosthecobacter

Tubulins, the protein constituents of the microtubule cytoskeleton, are present in all known eukaryotes but have never been found in the Bacteria or Archaea. Here we report the presence of two tubulin-like genes [bacterial tubulin a (btuba) and bacterial tubulin b (btubb)] in bacteria of the genus P...

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Published in:	Proceedings of the National Academy of Sciences - PNAS Vol. 99; no. 26; pp. 17049 - 17054
Main Authors:	Jenkins, Cheryl, Samudrala, Ram, Anderson, Iain, Hedlund, Brian P., Petroni, Giulio, Michailova, Natasha, Pinel, Nicolas, Overbeek, Ross, Rosati, Giovanna, Staley, James T.
Format:	Journal Article
Language:	English
Published:	United States National Academy of Sciences 24-12-2002 National Acad Sciences
Subjects:	Archaea Bacteria Base Sequence Biological Sciences Caulobacter - classification Caulobacter - genetics Dimers Eukaryotic cells Evolution Genes Genes, Bacterial Genomes Microbiology Microscopy, Electron Models, Molecular Molecular Sequence Data Monomers Phylogenetics Phylogeny Proteins Reverse transcriptase polymerase chain reaction Tubulin - genetics Verrucomicrobia
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Summary:	Tubulins, the protein constituents of the microtubule cytoskeleton, are present in all known eukaryotes but have never been found in the Bacteria or Archaea. Here we report the presence of two tubulin-like genes [bacterial tubulin a (btuba) and bacterial tubulin b (btubb)] in bacteria of the genus Prosthecobacter (Division Verrucomicrobia). In this study, we investigated the organization and expression of these genes and conducted a comparative analysis of the bacterial and eukaryotic protein sequences, focusing on their phylogeny and 3D structures. The btuba and btubb genes are arranged as adjacent loci within the genome along with a kinesin light chain gene homolog. RT-PCR experiments indicate that these three genes are cotranscribed, and a probable promoter was identified upstream of btuba. On the basis of comparative modeling data, we predict that the Prosthecobacter tubulins are monomeric, unlike eukaryotic α and β tubulins, which form dimers and are therefore unlikely to form microtubule-like structures. Phylogenetic analyses indicate that the Prosthecobacter tubulins are quite divergent and do not support recent horizontal transfer of the genes from a eukaryote. The discovery of genes for tubulin in a bacterial genus may offer new insights into the evolution of the cytoskeleton.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 Edited by Carl R. Woese, University of Illinois at Urbana–Champaign, Urbana, IL, and approved November 6, 2002 To whom correspondence should be addressed. E-mail: jtstaley@u.washington.edu. This paper was submitted directly (Track II) to the PNAS office. Data deposition: The sequences reported in this paper have been deposited in the GenBank database (accession nos. –).
ISSN:	0027-8424 1091-6490
DOI:	10.1073/pnas.012516899