Hindawi Publishing Corporation International Journal of Microbiology Volume 2010, Article ID 187373, 21 pages doi:10.1155/2010/187373 Research Article Functional Promiscuity of Homologues of the Bacterial ArsA ATPases Rostislav Castillo and Milton H. Saier Jr. Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116, USA Correspondence should be addressed to Milton H. Saier Jr.,
[email protected] Received 3 July 2010; Accepted 7 September 2010 Academic Editor: Ingolf Figved Nes Copyright © 2010 R. Castillo and M. H. Saier Jr. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. TheArsAATPaseofE. coli plays an essential role in arsenic detoxification. Published evidence implicates ArsA in the energization of As(III) efflux via the formation of an oxyanion-translocating complex with ArsB. In addition, eukaryotic ArsA homologues have several recognized functions unrelated to arsenic resistance. By aligning ArsA homologues, constructing phylogenetic trees, examining ArsA encoding operons, and estimating the probable coevolution of these homologues with putative transporters and auxiliary proteins unrelated to ArsB, we provide evidence for new functions for ArsA homologues. They may play roles in carbon starvation, gas vesicle biogenesis, and arsenic resistance. The results lead to the proposal that ArsA homologues energize four distinct and nonhomologous transporters, ArsB, ArsP, CstA, and Acr3. 1. Introduction ArsB is a 12 α-helix transmembrane spanning (TMS) pump extruding As(III) and Sb(III) [6]. Transport via ArsB Arsenical species present threats to all organisms. The can be energized by the pmf or by forming an oxyanion- two predominant states of inorganic arsenic are arsenate translocating complex with the catalytic ArsA subunit, [As(V)] and arsenite [As(III)].