Tamber Sandeep, Hancock Robert E W
Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada.
FEMS Microbiol Lett. 2006 Jul;260(1):23-9. doi: 10.1111/j.1574-6968.2006.00293.x.
The OprD family of specific porins in Pseudomonas aeruginosa comprises 19 members, some of which have been demonstrated to facilitate the uptake of specific compounds into the cell. The members of this family share considerable amino acid sequence similarity (46-57%), which is unusual among porin molecules. In this work, we sought to establish whether this sequence conservation was the basis for other shared aspects of this family. The transcriptional profiles of eight relatively well-characterized OprD homologs were assessed in cells grown on a variety of carbon compounds. The expression of these paralogous proteins correlated with their phylogenetic distribution into two subfamilies in that the three members of the OpdK subfamily were induced by their specific (organic acid) substrates while the five members of the amino-acid/peptide-specific OprD subfamily appeared to be constitutively expressed. Functional overlap with respect to arginine transport was observed between two members of the latter subfamily, the basic amino acid-specific porin, OprD, and the glycine-glutamate-specific porin, OpdP. The impact of this apparent functional redundancy on the genetic fitness of P. aeruginosa is discussed.
铜绿假单胞菌中特定孔蛋白的OprD家族由19个成员组成，其中一些成员已被证明有助于特定化合物进入细胞。该家族成员具有相当高的氨基酸序列相似性（46 - 57%），这在孔蛋白分子中并不常见。在这项研究中，我们试图确定这种序列保守性是否是该家族其他共同特征的基础。在以多种碳化合物为生长底物的细胞中评估了八个特征相对明确的OprD同源物的转录谱。这些旁系同源蛋白的表达与其系统发育分布相关，分为两个亚家族，即OpdK亚家族的三个成员由其特定（有机酸）底物诱导表达，而氨基酸/肽特异性OprD亚家族的五个成员似乎组成性表达。在后者亚家族的两个成员之间观察到了在精氨酸转运方面的功能重叠，即碱性氨基酸特异性孔蛋白OprD和甘氨酸 - 谷氨酸特异性孔蛋白OpdP。讨论了这种明显的功能冗余对铜绿假单胞菌遗传适应性的影响。
