Rhizobial Lipopolysaccharides Essential for Infection

感染必需的根瘤菌脂多糖

基本信息

批准号：
8008946
负责人：
RUSSELL W CARLSON
金额：
$ 12万
依托单位：
UNIVERSITY OF GEORGIA
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-01-28 至 2010-12-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Rhizobium-legume symbioses involve processes that are fundamental to all bacterial-host interactions. These include (a.) prokaryotic-eukaryotic recognition, (b.) interaction with the host defense mechanism, and (c.) bacterial and host differentiation processes (i.e. formation of nitrogen-fixing bacteroids and root nodules, respectively). As with animal pathogens, the invading rhizobia must adapt to the environment of the host to avoid destruction and persist in the host cell. These adaptations involve changes to cell surface polysaccharides, such as lipopolysaccharides (LPSs) and capsular polysaccharides. Rhizobium-legume symbiosis is an excellent model system to examine the molecular bases by which Gram-negative bacteria infect and survive within their host since both the bacteria and the host cells are viable throughout the infection process, and the LPSs from the invading bacteria can be isolated and characterized as a function of the infection process. The symbiosis system is particularly relevant to a number of intracellular pathogens that form chronic infections such as species of Brucella, Bartonella, Legionella, as well as Francisella. We have observed that unique structural features of Rhizobium LPSs are also present on LPSs from these pathogens. Our project focuses on the adaptation that rhizobia (R. etli and R. leguminosarum; symbionts of bean and pea, respectively) make to their LPSs as they encounter the stressful environment (e.g. changes in pH, osmolarity, oxygen tension, etc.) of the host cell. We hypothesize that unique structural features of rhizobial LPSs are essential for infection and persistence in the legume hosts. Unique structural features include a replacement of phosphate with galacturonic acid residues, oxidation of the lipid-A proximal glucosamine residue to 2-aminogluconate, and the presence of the very long chain fatty acid, 27- hydroxyoctacosaonic acid (27OHC28:0), on the lipid-A. Methylation and acetylation changes to the O-chain polysaccharide and an overall change in the hydrophobicity of the LPS and the whole rhizobial cell occur during symbiosis. Our Specific Aims are: (1.) characterize the modifications to the O-chain polysaccharide of the LPS during symbiosis, (2.) create specific LPS mutants and characterize their structural and symbiotic phenotypes, and (3.) determine how a 27OHC28:0-lacking mutant, acpXL::kan, is able to activate an alternative mechanism within the host cell.

描述（由申请人提供）：根瘤菌-豆科植物共生涉及对所有细菌-宿主相互作用至关重要的过程。这些包括（a.）原核-真核识别，（b.）与宿主防御机制的相互作用，以及（c.）细菌和宿主分化过程（即分别形成固氮类细菌和根瘤）。与动物病原体一样，入侵的根瘤菌必须适应宿主的环境，以避免破坏并持续存在于宿主细胞中。这些适应涉及细胞表面多糖的变化，例如脂多糖（LPS）和荚膜多糖。根瘤菌-豆科植物共生是一个很好的模型系统，用于检查革兰氏阴性细菌在宿主内感染和生存的分子基础，因为细菌和宿主细胞在整个感染过程中都是可行的，并且来自入侵细菌的脂多糖可以被根据感染过程进行分离和表征。共生系统与许多形成慢性感染的细胞内病原体特别相关，例如布鲁氏菌、巴尔通体、军团菌以及弗朗西斯氏菌。我们观察到，这些病原体的 LPS 上也存在根瘤菌 LPS 的独特结构特征。我们的项目重点关注根瘤菌（R.etli 和 R.leguminosarum；分别是菜豆和豌豆的共生体）在遇到压力环境（例如 pH 值、渗透压、氧张力等的变化）时对其 LPS 的适应。宿主细胞。我们假设根瘤菌脂多糖的独特结构特征对于豆类宿主的感染和持久性至关重要。独特的结构特征包括用半乳糖醛酸残基取代磷酸盐、脂质-A 近端葡萄糖胺残基氧化为 2-氨基葡萄糖酸盐，以及极长链脂肪酸 27- 羟基二十八烷酸 (27OHC28:0) 的存在。脂质-A。在共生过程中，O 链多糖发生甲基化和乙酰化，LPS 和整个根瘤细胞的疏水性发生整体变化。我们的具体目标是：(1.) 表征共生期间 LPS O 链多糖的修饰，(2.) 创建特定的 LPS 突变体并表征其结构和共生表型，以及 (3.) 确定 27OHC28 如何： 0-缺失突变体 acpXL::kan 能够激活宿主细胞内的替代机制。

项目成果

期刊论文数量（52）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

The nodPQ genes in Azospirillum brasilense Sp7 are involved in sulfation of lipopolysaccharides.

巴西固氮螺菌 Sp7 中的 nodPQ 基因参与脂多糖的硫酸化。

DOI：
10.1111/j.1462-2920.2005.00930.x
发表时间：
2005
期刊：
Environmental microbiology.
影响因子：
0
作者：
Vanbleu,Els;Choudhury,BiswaP;Carlson,RussellW;Vanderleyden,Jos
通讯作者：
Vanderleyden,Jos

The presence of a novel type of surface polysaccharide in Rhizobium meliloti requires a new fatty acid synthase-like gene cluster involved in symbiotic nodule development.

苜蓿根瘤菌中存在一种新型表面多糖，需要一种新的脂肪酸合酶样基因簇参与共生根瘤的发育。

DOI：
10.1111/j.1365-2958.1993.tb01653.x
发表时间：
1993
期刊：
Molecular microbiology
影响因子：
3.6
作者：
Petrovics,G;Putnoky,P;Reuhs,B;Kim,J;Thorp,TA;Noel,KD;Carlson,RW;Kondorosi,A
通讯作者：
Kondorosi,A

The pea nodule environment restores the ability of a Rhizobium leguminosarum lipopolysaccharide acpXL mutant to add 27-hydroxyoctacosanoic acid to its lipid A.

豌豆根瘤环境恢复了豆根瘤菌脂多糖acpXL突变体向其脂质A添加27-羟基二十八烷酸的能力。

DOI：
10.1128/jb.188.6.2126-2133.2006
发表时间：
2006
期刊：
Journal of bacteriology
影响因子：
3.2
作者：
Vedam,Vinata;Kannenberg,Elmar;Datta,Anup;Brown,Dusty;Haynes-Gann,JanineG;Sherrier,DJanine;Carlson,RussellW
通讯作者：
Carlson,RussellW

A lipopolysaccharide mutant of Bradyrhizobium japonicum that uncouples plant from bacterial differentiation.