Myers C R, Myers J M
Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee 53226.
J Bacteriol. 1992 Jun;174(11):3429-38. doi: 10.1128/jb.174.11.3429-3438.1992.
In gram-negative bacteria, numerous cell functions, including respiration-linked electron transport, have been ascribed to the cytoplasmic membrane. Gram-negative bacteria which use solid substrates (e.g., oxidized manganese or iron) as terminal electron acceptors for anaerobic respiration are presented with a unique problem: they must somehow establish an electron transport link across the outer membrane between large particulate metal oxides and the electron transport chain in the cytoplasmic membrane. When the metal-reducing bacterium Shewanella putrefaciens MR-1 is grown under anaerobic conditions and membrane fractions are purified from cells lysed by an EDTA-lysozyme-polyoxyethylene cetyl ether (Brij 58) protocol, approximately 80% of its membrane-bound cytochromes are localized in its outer membrane. These outer membrane cytochromes could not be dislodged by treatment with chaotropic agents or by increased concentrations of the nonionic detergent Brij 58, suggesting that they are integral membrane proteins. Cytochrome distribution in cells lysed by a French press protocol confirm the localization of cytochromes to the outer membrane of anaerobically grown cells. This novel cytochrome distribution could play a key role in the anaerobic respiratory capabilities of this bacterium, especially in its ability to mediate manganese and iron reduction.
在革兰氏阴性菌中，包括呼吸相关电子传递在内的许多细胞功能都归因于细胞质膜。以固体底物（如氧化锰或铁）作为厌氧呼吸终末电子受体的革兰氏阴性菌面临一个独特的问题：它们必须以某种方式在外膜上建立起大型颗粒金属氧化物与细胞质膜中电子传递链之间的电子传递联系。当金属还原菌腐败希瓦氏菌MR-1在厌氧条件下生长，并通过乙二胺四乙酸-溶菌酶-聚氧乙烯十六烷基醚（Brij 58）法从裂解细胞中纯化膜组分时，其约80%的膜结合细胞色素定位于外膜。这些外膜细胞色素不能通过用离液剂处理或增加非离子去污剂Brij 58的浓度而去除，这表明它们是整合膜蛋白。通过法式压榨法裂解细胞后的细胞色素分布证实了细胞色素定位于厌氧生长细胞的外膜。这种新的细胞色素分布可能在该细菌的厌氧呼吸能力中起关键作用，尤其是在其介导锰和铁还原的能力方面。
