Daviso Eugenio, Belenky Marina, Griffin Robert G, Herzfeld Judith
Department of Chemistry, Brandeis University, Waltham, Mass. 02454-9110, USA.
J Mol Microbiol Biotechnol. 2013;23(4-5):281-9. doi: 10.1159/000351340. Epub 2013 Aug 5.
The buoyancy organelles of aquatic microorganisms have to meet stringent specifications: allowing gases to equilibrate freely across the proteinaceous shell, preventing the condensation of water vapor inside the hollow cavity and resisting collapse under hydrostatic pressures that vary with column depth. These properties are provided by the 7- to 8-kDa gas vesicle protein A (GvpA), repeats of which form all but small, specialized portions of the shell. Magic angle spinning nuclear magnetic resonance is uniquely capable of providing high-resolution information on the fold and assembly of GvpA. Here we compare results for the gas vesicles of the haloarchaea Halobacterium salinarum with those obtained previously for the cyanobacterium Anabaena flos-aquae. The data suggest that the two organisms follow similar strategies for avoiding water condensation. On the other hand, in its relatively shallow habitat, H. salinarum is able to avoid collapse with a less costly GvpA fold than is adopted by A. flos-aquae.
允许气体在蛋白质外壳上自由平衡，防止空心腔内水蒸气凝结，并在随水柱深度变化的静水压力下抵抗坍塌。这些特性由7至8千道尔顿的气体囊泡蛋白A（GvpA）提供，其重复序列构成了外壳除小的特殊部分之外的所有部分。魔角旋转核磁共振能够独特地提供关于GvpA折叠和组装的高分辨率信息。在这里，我们将盐生盐杆菌的气体囊泡结果与之前对水华鱼腥藻获得的结果进行了比较。数据表明，这两种生物遵循相似的策略来避免水凝结。另一方面，在其相对较浅的栖息地中，盐生盐杆菌能够通过比水华鱼腥藻采用的成本更低的GvpA折叠来避免坍塌。
