趋磁细菌磁小体形成机制研究进展

磁小体(Magnetosome)是由趋磁细菌(Magnetotactic bacteria,MTB)体内合成并有生物膜包裹的纳米级磁性晶体,其形成过程是一个包括多种基因和蛋白参与并且受基因表达调控的酶催化过程.本文主要从铁离子吸收、磁小体膜形成、铁离子转运、生物矿化和磁小体链组装等5个方面来详细阐述磁小体的形成过程,重点介绍近年来分离和鉴定的相关基因和蛋白,并分析其在磁小体形成过程中的作用机制,同时还介绍了氧气、铁源和培养基成分等环境因素对磁小体形成的影响.尽管已经鉴别了大部分磁小体形成的相关基因,但是运用遗传学和生化分析手段阐明其作用机理仍然是一个挑战.磁小体形成机制的进一步研究和阐明将为其在生物技术领域的应用奠定基础.

Progress in Research on Formation Mechanism of Magnetosome in Magnetotactic Bacteria

Magnetosomes are membrane-encapsulated nano magnetic crystals which are synthesized intracellularly by magnetotactic bacteria(MTB).Magnetosome formation is a complicated process involving the expression of many genes and the actions of many proteins/enzymes.This article expatiates on the process of magnetosome formation in detail,which consists of five steps,namely iron uptake,magnetosome membrane formation,iron transport into the magnetosomes,biomineralization and assembly of magnetosome chains.It mainly focuses on introducing genes/proteins isolated and identified from each step in recent years and analyzing their functions in magnetosome formation.These genes clustere within a large unstable genomic region called the magnetosome island(MAI),especially within the conserved mamAB region,which is known to be essential for magnetosome formation.This article also underlines the effects of environmental factors such as oxygen,iron sources and culture medium constituents on magnetosome formation.Although most of the candidate genes involved in magnetosome formation have likely been identified,elucidation of their individual functions by genetics and biochemical analysis will remain a challenge for the next few years.Further researches on and better understanding in magnetosome formation mechanism will lay a foundation on greatly potential application of magnetosome in biotechnology field.