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DMSP SYNTHESIS VIA A NOVEL ENZYME IN CYANOBACTERIA AND DIVERSE BACTERIA

通过蓝藻和多种细菌中的新型酶合成 DMSP

基本信息

批准号：
NE/X014428/1
负责人：
David John Lea-Smith
金额：
$ 78.36万
依托单位：
University of East Anglia
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2023
资助国家：
英国
起止时间：
2023 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FX014428%2F1
关键词：
DMSP SYNTHESIS VIA NOVEL ENZYME

项目摘要

Dimethylsulfoniopropionate (DMSP) is an important and highly abundant organo-sulfur compound. It is synthesised by many algae, bacteria and some higher plants, where it is thought to be involved in chemotaxis, grazer deterrence, osmoprotection, cryoprotection, hydrostatic pressure protection and/or resistance to oxidative stress. DMSP, and its gaseous breakdown products, dimethyl sulfide (DMS) and methanethiol (MeSH) are the major biosources of sulfur transferred from the oceans to the atmosphere. Atmospheric DMS and MeSH are climate active gases (CAGs) that form aerosols and cloud condensation nuclei, which reduce the global radiation budget and 'cool' the local climate.It was previously thought that only Trichodesmium species of cyanobacteria and low proportions of marine bacteria produce DMSP at significant levels. However, our pilot work shows that many cyanobacteria, e.g. highly abundant marine Synechococcus and saltmarsh species, produce DMSP, as well as other important and abundant bacterial phyla (e.g. gammaproteobacteria). These microbes contain a gene that we term dsyC, which we show encodes the key S-methyltransferase enzyme that catalyses the committed and rate limiting step of DMSP synthesis. This work is important because dsyC genes occur in up to 5% of marine bacteria and are highly transcribed in Earth's photic waters and surface sediment, established from our analysis of the Tara Oceans and local datasets. In comparison, the other DMSP synthesis genes that we and others discovered (dsyB, DSYB, mmtN and TpMMT), encoding the key S-methyltransferase of alternate bacterial and algal DMSP biosynthesis pathways, are collectively far less abundant and transcribed than dsyC. Therefore, cyanobacteria and other diverse bacteria (cyano/bacteria) with DsyC could be very significant contributors to global production of DMSP, and, thus, of CAGs derived from it. This would be a paradigm-shifting finding, showing that cyano/bacteria, pretty much ignored as significant DMSP producers, are large-scale contributors to global production. However, without the multidisciplinary work planned here we are unable to make such statements.The first major goal will be to establish the environmental conditions under which DMSP is produced in cyano/bacteria that have DsyC homologues. We will then generate dsyC knockouts in marine Synechococcus species and a selection of other bacteria with dsyC. Growth of wild-type and mutant strains will then be compared under a range of environmental or stress conditions to assess the role of DMSP in these bacteria and importantly the major environmental drivers of DsyC-dependent DMSP synthesis. In conjunction, we will determine the amount of DMSP per cell and synthesis rates in wild-type and mutant samples. The next goal will be to determine the key features of the DsyC enzyme. To address this, we will examine the enzymatic activity and substrate affinity of DsyC from a range of cyano/bacteria to identify the key amino acid residues that could determine whether they are of a high activity or low activity type. Finally, via analysis of cyano/bacterial samples from a broad range of oligotrophic and coastal waters, and a seasonal study of saltmarsh cyanobacterial mats, we will quantify DMSP and CAG levels and synthesis rates and compare these to laboratory cultured model organisms. This will allow us to estimate annual, global production rates of DMSP by marine Synechococcus and potentially Prochlorococcus species, localised production by all species in Western Pacific and Eastern Indian oceans, and localised saltmarshes and potential production of DMS and therefore the environmental impact of cyanobacterial DMSP production.

二甲基磺基丙酸酯(DMSP)是一种重要的、含量很高的有机硫化合物。它是由许多藻类、细菌和一些高等植物合成的，在这些植物中，它被认为参与了趋化性、食草动物威慑、渗透保护、低温保护、静水压力保护和/或抵抗氧化应激。DMSP及其气体分解产物二甲基硫(DMS)和甲硫醇(MESH)是从海洋转移到大气中的硫的主要生物来源。大气DMS和Mesh是气候活性气体(CAG)，它们形成气溶胶和云凝结核，减少全球辐射收支，使当地气候变冷。以前人们认为，只有蓝藻中的毛霉菌和低比例的海洋细菌才会产生显著水平的DMSP。然而，我们的试点工作表明，许多蓝藻，如高度丰富的海洋聚球藻和盐沼物种，产生DMSP，以及其他重要和丰富的细菌门(如伽马保护细菌)。这些微生物含有一种我们称之为dsyC的基因，我们发现该基因编码关键的S甲基转移酶，该酶催化DMSP合成的关键和限速步骤。这项工作很重要，因为dsyC基因存在于多达5%的海洋细菌中，并在地球的光水域和表层沉积物中高度转录，这是通过我们对Tara海洋和当地数据集的分析而建立的。相比之下，我们和其他人发现的其他DMSP合成基因(dsyB、dsyB、MmtN和TpMMT)编码交替的细菌和藻类DMSP生物合成途径的关键S甲基转移酶，总体上远不如dsyC丰富，也没有dsyC转录。因此，蓝藻和其他带有DsyC的不同细菌(氰基/细菌)可能对全球DMSP的生产以及由此产生的CAGs做出非常重要的贡献。这将是一个改变范式的发现，表明氰基/细菌是全球产量的大规模贡献者，作为DMSP的重要生产者，它们几乎被忽视了。然而，如果没有这里计划的多学科工作，我们无法做出这样的声明。第一个主要目标将是建立在具有DsyC同源物的氰基/细菌中产生DMSP的环境条件。然后，我们将在海洋聚球菌种中产生dsyC敲除，并使用dsyC选择其他细菌。然后，将比较野生型和突变菌株在一系列环境或压力条件下的生长，以评估DMSP在这些细菌中的作用，以及重要的是依赖于DsyC的DMSP合成的主要环境驱动因素。同时，我们将确定每个细胞的DMSP数量以及野生型和突变样本的合成速率。下一个目标将是确定DsyC酶的关键特性。为了解决这个问题，我们将检测一系列氰基/细菌的DsyC的酶活性和底物亲和力，以确定可以确定它们是高活性类型还是低活性类型的关键氨基酸残基。最后，通过对广泛的贫营养和沿海水域的氰基/细菌样本的分析，以及对盐沼蓝藻垫子的季节性研究，我们将量化DMSP和CAG的水平和合成速率，并将这些与实验室培养的模式生物进行比较。这将使我们能够估计海洋聚球藻和潜在的原氯球菌物种对DMSP的年度全球生产量、西太平洋和东印度洋所有物种的局部生产量、局部盐沼和DMS的潜在生产量，从而估计蓝藻DMSP生产对环境的影响。

项目成果

期刊论文数量（6）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Deep-sea Bacteroidetes from the Mariana Trench specialize in hemicellulose and pectin degradation typically associated with terrestrial systems.

DOI：
10.1186/s40168-023-01618-7
发表时间：
2023-08-07
期刊：
Microbiome
影响因子：
15.5
作者：
通讯作者：

CyanoCyc cyanobacterial web portal

DOI：
10.3389/fmicb.2024.1340413
发表时间：
2024-01-31
期刊：
FRONTIERS IN MICROBIOLOGY
影响因子：
5.2
作者：
Moore，Lisa R.;Caspi，Ron;Karp，Peter D.
通讯作者：
Karp，Peter D.

SAR92 clade bacteria are potentially important DMSP degraders and sources of climate-active gases in marine environments.

DOI：
10.1128/mbio.01467-23
发表时间：
2023-12-19
期刊：
MBIO
影响因子：
6.4
作者：
He, Xiao-Yan;Liu, Ning-Hua;Liu, Ji-Qing;Peng, Ming;Teng, Zhao-Jie;Gu, Tie-Ji;Chen, Xiu-Lan;Chen, Yin;Wang, Peng;Li, Chun-Yang;Todd, Jonathan D.;Zhang, Yu-Zhong;Zhang, Xi-Ying
通讯作者：
Zhang, Xi-Ying

Novel dimethylsulfoniopropionate biosynthesis enzymes in diverse marine bacteria, cyanobacteria and abundant algae

多种海洋细菌、蓝细菌和丰富藻类中的新型二甲基磺基丙酸生物合成酶