A 3-Dimensional Trimeric beta-Barrel Model for Chlamydia MOMP Contains Conserved and Novel Elements of Gram-Negative Bacterial Porins

作者：Feher Victoria A; Randall Arlo; Baldi Pierre; Bush Robin M; de la Maza Luis M; Amaro Rommie E^*

来源：PLos One, 2013, 8(7): e68934.

DOI：10.1371/journal.pone.0068934

Chlamydia trachomatis is the most prevalent cause of bacterial sexually transmitted diseases and the leading cause of preventable blindness worldwide. Global control of Chlamydia will best be achieved with a vaccine, a primary target for which is the major outer membrane protein, MOMP, which comprises similar to 60% of the outer membrane protein mass of this bacterium. In the absence of experimental structural information on MOMP, three previously published topology models presumed a16-stranded barrel architecture. Here, we use the latest beta-barrel prediction algorithms, previous 2D topology modeling results, and comparative modeling methodology to build a 3D model based on the 16-stranded, trimeric assumption. We find that while a 3D MOMP model captures many structural hallmarks of a trimeric 16-stranded beta-barrel porin, and is consistent with most of the experimental evidence for MOMP, MOMP residues 320-334 cannot be modeled as beta-strands that span the entire membrane, as is consistently observed in published 16-stranded beta-barrel crystal structures. Given the ambiguous results for beta-strand delineation found in this study, recent publications of membrane beta-barrel structures breaking with the canonical rule for an even number of beta-strands, findings of beta-barrels with strand-exchanged oligomeric conformations, and alternate folds dependent upon the lifecycle of the bacterium, we suggest that although the MOMP porin structure incorporates canonical 16-stranded conformations, it may have novel oligomeric or dynamic structural changes accounting for the discrepancies observed.

• 出版日期2013-7-25