Evolutionary relationships of ATP-Binding Cassette (ABC) uptake porters

BMC Microbiology

Research Article

Åke Västermark¹  Milton H Saier¹  Eric I Sun²  Wei Hao Zheng³  Vamsee Reddy⁴  Maksim A Shlykov⁵ 

[1] Department of Molecular Biology, University of California at San Diego, 92093-0116, La Jolla, CA, USA;Department of Molecular Biology, University of California at San Diego, 92093-0116, La Jolla, CA, USA;Burnham Institute, La Jolla, CA, USA;Department of Molecular Biology, University of California at San Diego, 92093-0116, La Jolla, CA, USA;Medical College of Wisconsin, Milwaukee, WI, USA;Department of Molecular Biology, University of California at San Diego, 92093-0116, La Jolla, CA, USA;University of Calgary, Calgary, AB, Canada;Department of Molecular Biology, University of California at San Diego, 92093-0116, La Jolla, CA, USA;University of Michigan Medical School, Ann Arbor, MI, USA;

关键词: ATP-Binding Cassette;    ABC;    Uptake;    Transport proteins;    Membranes;    Protein superfamilies;    Comparisons;   

DOI  :  10.1186/1471-2180-13-98

 received in 2012-10-29, accepted in 2013-04-19,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundThe ATP-Binding Cassette (ABC) functional superfamily includes integral transmembrane exporters that have evolved three times independently, forming three families termed ABC1, ABC2 and ABC3, upon which monophyletic ATPases have been superimposed for energy-coupling purposes [e.g., J Membr Biol 231(1):1-10, 2009]. The goal of the work reported in this communication was to understand how the integral membrane constituents of ABC uptake transporters with different numbers of predicted or established transmembrane segments (TMSs) evolved. In a few cases, high resolution 3-dimensional structures were available, and in these cases, their structures plus primary sequence analyses allowed us to predict evolutionary pathways of origin.ResultsAll of the 35 currently recognized families of ABC uptake proteins except for one (family 21) were shown to be homologous using quantitative statistical methods. These methods involved using established programs that compare native protein sequences with each other, after having compared each sequence with thousands of its own shuffled sequences, to gain evidence for homology. Topological analyses suggested that these porters contain numbers of TMSs ranging from four or five to twenty. Intragenic duplication events occurred multiple times during the evolution of these porters. They originated from a simple primordial protein containing 3 TMSs which duplicated to 6 TMSs, and then produced porters of the various topologies via insertions, deletions and further duplications. Except for family 21 which proved to be related to ABC1 exporters, they are all related to members of the previously identified ABC2 exporter family. Duplications that occurred in addition to the primordial 3 → 6 duplication included 5 → 10, 6 → 12 and 10 → 20 TMSs. In one case, protein topologies were uncertain as different programs gave discrepant predictions. It could not be concluded with certainty whether a 4 TMS ancestral protein or a 5 TMS ancestral protein duplicated to give an 8 or a 10 TMS protein. Evidence is presented suggesting but not proving that the 2TMS repeat unit in ABC1 porters derived from the two central TMSs of ABC2 porters. These results provide structural information and plausible evolutionary pathways for the appearance of most integral membrane constituents of ABC uptake transport systems.ConclusionsAlmost all integral membrane uptake porters of the ABC superfamily belong to the ABC2 family, previously established for exporters. Most of these proteins can have 5, 6, 10, 12 or 20 TMSs per polypeptide chain. Evolutionary pathways for their appearance are proposed.

【 授权许可】

Unknown   
© Zheng et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.