Magnuson Ann, Cardona Tanai
Department of Chemistry - Ångström Laboratory, Uppsala University, Box 523, SE-75120, Uppsala, Sweden.
Department of Life Sciences, Imperial College London, London SW7 2AZ, England, UK.
Biochim Biophys Acta. 2016 Mar;1857(3):309-19. doi: 10.1016/j.bbabio.2015.10.016. Epub 2015 Nov 9.
Multicellular cyanobacteria form different cell types in response to environmental stimuli. Under nitrogen limiting conditions a fraction of the vegetative cells in the filament differentiate into heterocysts. Heterocysts are specialized in atmospheric nitrogen fixation and differentiation involves drastic morphological changes on the cellular level, such as reorganization of the thylakoid membranes and differential expression of thylakoid membrane proteins. Heterocysts uphold a microoxic environment to avoid inactivation of nitrogenase by developing an extra polysaccharide layer that limits air diffusion into the heterocyst and by upregulating heterocyst-specific respiratory enzymes. In this review article, we summarize what is known about the thylakoid membrane in heterocysts and compare its function with that of the vegetative cells. We emphasize the role of photosynthetic electron transport in providing the required amounts of ATP and reductants to the nitrogenase enzyme. In the light of recent high-throughput proteomic and transcriptomic data, as well as recently discovered electron transfer pathways in cyanobacteria, our aim is to broaden current views of the bioenergetics of heterocysts. This article is part of a Special Issue entitled Organization and dynamics of bioenergetic systems in bacteria, edited by Conrad Mullineaux.
多细胞蓝细菌会根据环境刺激形成不同的细胞类型。在氮限制条件下，丝状藻体中的一部分营养细胞会分化为异形胞。异形胞专门进行大气固氮，其分化涉及细胞水平上剧烈的形态变化，如类囊体膜的重组以及类囊体膜蛋白的差异表达。异形胞通过形成一层额外的多糖层来限制空气扩散进入异形胞，并上调异形胞特异性呼吸酶，从而维持微氧环境，以避免固氮酶失活。在这篇综述文章中，我们总结了关于异形胞中类囊体膜的已知信息，并将其功能与营养细胞的功能进行比较。我们强调光合电子传递在为固氮酶提供所需量的ATP和还原剂方面的作用。鉴于最近的高通量蛋白质组学和转录组学数据，以及蓝细菌中最近发现的电子传递途径，我们的目标是拓宽当前对异形胞生物能量学的认识。本文是由康拉德·穆利纳克斯编辑的名为《细菌生物能量系统的组织与动力学》特刊的一部分。
