Proteome Analysis of Magnetite Crystal Formation Related Proteins Based on Genomic Information

趋磁细菌通过在水生环境中积累微量铁离子产生纳米级细胞内磁性颗粒（生物磁石）。不同的晶体形态和组成是物种或菌株依赖的，这意味着高度的生物控制。然而，生物磁铁矿形状控制的完整过程的细节仍不清楚。为了阐明生物磁体的形状控制机制，对产生子弹状生物磁体的Desulfovibrio magneticus RS-1进行了全面的蛋白质组学和基因组分析。菌株RS-1的大规模培养和纳米- lc串联质谱法对蛋白的灵敏检测，鉴定出176种生物磁铁矿膜蛋白。然后将鉴定的蛋白与从产生立方八面体生物磁石的Magnetospirillum magneticum AMB-1中提取的生物磁石膜蛋白进行比较。经比较，菌株RS-1与菌株AMB-1的蛋白分类基本一致。基因定位还揭示了另一个编码生物磁铁矿相关蛋白的基因组岛的存在，这与已知的生物磁铁矿形成相关的趋磁细菌基因组岛不同。对菌株RS-1生物磁铁矿膜蛋白的分析和与这些蛋白相关的2个基因组岛的鉴定表明，这些蛋白不是来自基因组中的单个基因区域，而是可能对生物磁铁矿形状控制有一个新的和独特的认识。在鉴定的蛋白质中，一些蛋白质与其他趋磁细菌中先前表征的蛋白质有相似之处，同时还鉴定了可能参与生物磁铁矿形成的新蛋白质。利用从生物磁铁矿形成过程中确定的蛋白质的部分序列中提取的肽段进行功能分析表明，该蛋白质可能在生物磁铁矿的形状控制中发挥作用。对类似蛋白的进一步研究将进一步阐明生物磁石的独特形态及其在该细菌中的作用机制。从不同形状的生物磁铁矿中鉴定出的生物磁铁矿相关蛋白的组合应用，可以并将扩大体外合成各种形状磁铁矿的可能性。少

Magnetotactic bacteria produce nano-sized intracellular magnetic particles (biomagnetites) by accumulating trace amounts of iron ions in aquatic environments. The different crystal morphologies and compositions are species- or strain-dependent, implying a high degree of biological control. However, details of the complete process of biomagnetite shape control still remain unclear. To elucidate the shape control mechanism of biomagnetites, comprehensive proteomic and genome analyses were performed against Desulfovibrio magneticus RS-1 which produces bullet-shaped biomagnetites. Mass cultivation of strain RS-1 and sensitive detection of proteins using nano-LC tandem mass spectrometry enabled the identification of 176 biomagnetite membrane proteins. The identified proteins were then compared with biomagnetite membrane proteins extracted from Magnetospirillum magneticum AMB-1, which produces cubo-octahedral biomagnetites. Upon comparison of both the bacterial strains, the identified protei … More ns from strain RS-1 showed similar protein classifications with that of strain AMB-1. Gene mapping of the identified proteins also revealed the existence of another genomic island coding for biomagnetite-associated proteins which is different from known biomagnetite formation related genomic islands of magnetotactic bacteria. The analyses performed against the biomagnetite membrane proteins of strain RS-1 and the identification of 2 genomic islands related to these proteins suggests that the proteins are not derived from a single gene region in the genome but instead may impose a new and unique understanding of biomagnetite shape control. Among the identified proteins, several proteins shared similarities with previously characterized proteins in other magnetotactic bacteria while novel proteins likely to be involved in biomagnetite formation were also identified. Functional analysis using peptides derived from partial sequences of an identified protein proposed to be involved in biomagnetite formation indicated that the protein showed a possible role in the shape control of biomagnetites. Further investigation of similar proteins will further clarify the unique morphology of biomagnetites and its mechanism in this bacterium. The combinatorial application of biomagnetite-associated proteins which were identified from different shaped biomagnetites, can and will expand the possibilities for various shaped magnetite synthesis in vitro. Less