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厌氧共生菌通过反硝化作用为纤毛宿主提供能量
2021-03-07 21:41

德国马克斯·普朗克海洋微生物研究所Jana Milucka、Jon S. Graf等研究人员合作发现,厌氧共生菌通过反硝化作用为纤毛宿主提供能量。该项研究成果于2021年3月3日在线发表在《自然》杂志上。

研究人员发现了“ Candidatus Azoamicus ciliaticola”,它是厌氧纤毛虫的特有内共生体,在呼吸作用和为真核宿主提供能量方面发挥着重要作用。“Candidatus A. ciliaticola”包含一个高度减少的0.29-Mb基因组,该基因组编码用于核心信息处理、电子传输链、截短的三羧酸循环、ATP生成和铁硫簇生物合成的核心基因。基因组编码的是呼吸反硝化途径,而不是有氧末端氧化酶,这使宿主能够呼吸硝酸盐而不是氧气。

“Candidatus A. ciliaticola”及其纤毛寄主代表了一种共生的例子,这种共生是基于ATP形式的能量转移而不是营养。这一发现提示,具有线粒体残留物的真核生物可能进一步获得提供能量的内共生体来补充或替代其线粒体功能。 

据了解,线粒体是特化的真核细胞器,在氧气呼吸和能量产生中具有专门的功能。它们大约在20亿年前从一个自由生存的细菌祖先(可能是一种α变形蛋白细菌)进化而来,这个过程被称为内共生。此后,许多单细胞真核生物适应了缺氧栖息地的生活,其线粒体经历了进一步的减向进化。结果,具有线粒体残余的专性厌氧真核生物主要从发酵中获取能量。

附:英文原文

Title: Anaerobic endosymbiont generates energy for ciliate host by denitrification

Author: Jon S. Graf, Sina Schorn, Katharina Kitzinger, Soeren Ahmerkamp, Christian Woehle, Bruno Huettel, Carsten J. Schubert, Marcel M. M. Kuypers, Jana Milucka

Issue&Volume: 2021-03-03

Abstract: Mitochondria are specialized eukaryotic organelles that have a dedicated function in oxygen respiration and energy production. They evolved about 2 billion years ago from a free-living bacterial ancestor (probably an alphaproteobacterium), in a process known as endosymbiosis1,2. Many unicellular eukaryotes have since adapted to life in anoxic habitats and their mitochondria have undergone further reductive evolution3. As a result, obligate anaerobic eukaryotes with mitochondrial remnants derive their energy mostly from fermentation4. Here we describe ‘Candidatus Azoamicus ciliaticola’, which is an obligate endosymbiont of an anaerobic ciliate and has a dedicated role in respiration and providing energy for its eukaryotic host. ‘Candidatus A. ciliaticola’ contains a highly reduced 0.29-Mb genome that encodes core genes for central information processing, the electron transport chain, a truncated tricarboxylic acid cycle, ATP generation and iron–sulfur cluster biosynthesis. The genome encodes a respiratory denitrification pathway instead of aerobic terminal oxidases, which enables its host to breathe nitrate instead of oxygen. ‘Candidatus A. ciliaticola’ and its ciliate host represent an example of a symbiosis that is based on the transfer of energy in the form of ATP, rather than nutrition. This discovery raises the possibility that eukaryotes with mitochondrial remnants may secondarily acquire energy-providing endosymbionts to complement or replace functions of their mitochondria.

DOI: 10.1038/s41586-021-03297-6

Source: https://www.nature.com/articles/s41586-021-03297-6

Nature:《自然》,创刊于1869年。隶属于施普林格·自然出版集团,最新IF:69.504
官方网址:http://www.nature.com/
投稿链接:http://www.nature.com/authors/submit_manuscript.html


本期文章:《自然》:Online/在线发表

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