PduA is a shell protein of polyhedral organelles involved in coenzyme B12-dependent degradation of 1,2-propanediol in Salmonella enterica serovar typhimurium LT2
PduA is a shell protein of polyhedral organelles involved in coenzyme B12-dependent degradation of 1,2-propanediol in Salmonella enterica serovar typhimurium LT2
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DOI：
10.1128/jb.184.5.1253-1261.2002
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发表时间：
2002-03-01
影响因子：
3.2
通讯作者：
Bobik, TA
中科院分区：
文献类型：
--
作者：
Havemann, GD;Sampson, EM;Bobik, TA
肠沙门氏菌形成多面体细胞器，参与辅酶B-12依赖的1，2-丙二醇的降解。这些细胞器被认为是由一个蛋白质架子组成，它包裹着依赖辅酶B-12的二醇脱水酶和可能参与1，2-丙二醇降解的其他酶。这些细胞器的功能尚不清楚，也没有关于其结构的详细研究报道。细胞器形成和1，2-丙二醇降解所需的基因位于1，2-丙二醇利用(PDU)基因，但参与细胞器形成的特定基因尚未确定。在这里，我们证明了pduA基因编码一种壳蛋白，它是形成依赖辅酶B-12的1，2-丙二醇降解所需的多面体细胞器所必需的。从重组大肠杆菌中纯化了His(6)-PduA融合蛋白，并用于制备多克隆抗体。获得的抗PduA抗体通过减法得到部分纯化，并用于证明PduA蛋白定位于多面体细胞器的外壳。此外，电子显微镜研究证实，携带非极性pduA突变的菌株不能形成细胞器。这些结果表明，pduA基因是细胞器形成所必需的，表明pduA蛋白是这些细胞器外壳的结构成分。还对非极性突变体pdu4进行了生理研究。这些突变株在低浓度的1，2-丙二醇下的生长与野生型菌株相似，但在高浓度的生长底物存在下表现出一段时间的中断生长。生长测试还表明，在低维生素B-12浓度下，一个非极性的pdu4缺失突变株比野生株生长得更快。这些结果表明，肠链球菌在1，2-丙二醇上生长时形成的多面体细胞器不涉及1，2-丙二醇或辅酶B-12的浓度，但与这些细胞器适度产生醛以将毒性降至最低的假设一致。
Salmonella enterica forms polyhedral organelles involved in coenzyme B-12-dependent 1,2-propanediol degradation. These organelles are thought to consist of a proteinaceous shelf that encases coenzyme B-12-dependent diol dehydratase and perhaps other enzymes involved in 1,2-propanediol degradation. The function of these organelles is unknown, and no detailed studies of their structure have been reported. Genes needed for organelle formation and for 1,2-propanediol degradation are located at the 1,2-propanediol utilization (pdu) locus, but the specific genes involved in organelle formation have not been identified. Here, we show that the pduA gene encodes a shell protein required for the formation of polyhedral organelles involved in coenzyme B-12-dependent 1,2-propanediol degradation. A His(6)-PduA fusion protein was purified from a recombinant Escherichia coli strain and used for the preparation of polyclonal antibodies. The anti-PduA antibodies obtained were partially purified by a subtraction procedure and used to demonstrate that the PduA protein localized to the shell of the polyhedral organelles. In addition, electron microscopy studies established that strains with nonpolar pduA mutations were unable to form organelles. These results show that the pduA gene is essential for organelle formation and indicate that the PduA protein is a structural component of the shell of these organelles. Physiological studies of nonpolar pdu4 mutants were also conducted. Such mutants grew similarly to the wild-type strain at low concentrations of 1,2-propanediol but exhibited a period of interrupted growth in the presence of higher concentrations of this growth substrate. Growth tests also showed that a nonpolar pdu4 deletion mutant grew faster than the wild-type strain at low vitamin B-12 concentrations. These results suggest that the polyhedral organelles formed by S. enterica during growth on 1,2-propanediol are not involved in the concentration of 1,2-propanediol or coenzyme B-12, but are consistent with the hypothesis that these organelles moderate aldehyde production to minimize toxicity.