盡管許多生物性的屏障和區(qū)隔分界是由基于脂質(zhì)的膜所形成的,，但人們越來越多地了解到，在細胞內(nèi)還有基于蛋白質(zhì)的區(qū)室可作為與外界隔絕的環(huán)境,。許多細菌細胞中含有這樣的微區(qū)室，它們將特別的代謝過程（涉及不穩(wěn)定性或毒性代謝物）進行隔離而起著簡單的細胞器的作用,。
在2010年1月1日刊的《科學(xué)》雜志中,，Tanaka 等人報告了在大腸桿菌中隔絕乙醇胺代謝的某一微區(qū)室的四種主要蛋白成分的高解析度晶體結(jié)構(gòu)。這一區(qū)室可防止乙醛釋放到細胞的其它區(qū)域,，從而減輕了因過多的乙醛而可能造成的毒性影響,。盡管這四種蛋白質(zhì)具有相似的3維交疊，但它們?nèi)匀挥衅洫毺氐慕Y(jié)構(gòu)特征,，這可以解釋它們在該微區(qū)室中所扮演的獨特作用：例如在蛋白外殼中設(shè)置通過孔隙而進行的分子轉(zhuǎn)運的門徑,，或與核酸進行結(jié)合。（生物谷Bioon.com）
生物谷推薦原始出處：
Science 1 January 2010: DOI: 10.1126/science.1179513
Structure and Mechanisms of a Protein-Based Organelle in Escherichia coli
Shiho Tanaka,1 Michael R. Sawaya,2,3 Todd O. Yeates1,3,4,*
Many bacterial cells contain proteinaceous microcompartments that act as simple organelles by sequestering specific metabolic processes involving volatile or toxic metabolites. Here we report the three-dimensional (3D) crystal structures, with resolutions between 1.65 and 2.5 angstroms, of the four homologous proteins (EutS, EutL, EutK, and EutM) that are thought to be the major shell constituents of a functionally complex ethanolamine utilization (Eut) microcompartment. The Eut microcompartment is used to sequester the metabolism of ethanolamine in bacteria such as Escherichia coli and Salmonella enterica. The four Eut shell proteins share an overall similar 3D fold, but they have distinguishing structural features that help explain the specific roles they play in the microcompartment. For example, EutL undergoes a conformational change that is probably involved in gating molecular transport through shell protein pores, whereas structural evidence suggests that EutK might bind a nucleic acid component. Together these structures give mechanistic insight into bacterial microcompartments.
1 Department of Chemistry and Biochemistry, University of California Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095, USA.
2 Howard Hughes Medical Institute, University of California Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095, USA.
3 Univeristy of California Los Angeles, Department of Energy Institute for Genomics and Proteomics, 611 Charles Young Drive East, Los Angeles, CA 90095, USA.
4 Molecular Biology Institute, University of California Los Angeles 611 Charles Young Drive East, Los Angeles, CA 90095, USA.
