NodS: Difference between revisions
From Proteopedia
Jump to navigationJump to search
David Canner (talk | contribs) No edit summary |
No edit summary |
||
| Line 3: | Line 3: | ||
==Biological significance== | ==Biological significance== | ||
[[Image:Nods reaction.png|751px|left|thumb|Methylation reaction catalyzed by NodS]] | |||
===Rhizobia-legumes symbiosis=== | ===Rhizobia-legumes symbiosis=== | ||
The endosymbiotic relationship between nitrogen-fixing rhizobial bacteria and certain plants (legumes) is of the utmost importance for the nitrogen cycle in the biosphere and hence an object of intense study by specialists from various areas of biology. What is more, although the use of artificial nitrogen-containing fertilizers made it possible to bypass the strict dependence on this process, its understanding is still crucial for the efficient agriculture. Biological nitrogen fixation requires [[nitrogenase]], an enzyme present in, among others, rhizobial bacteria but absent in plants. The rhizobia are a diverse range of soil bacteria. It is thought that after the symbiotic capabilities were first acquired by some of them, they spread by means of horizontal transfer of a plasmid or genomic island containing genes important for the process. The symbiotic relationship between the two symbionts depends on the formation of invasion structures (nodules) by the host, allowing bacteria to enter the plant root, colonize a specific type of cells and be transformed into bacteroids which perform nitrogen fixation. As complementarity between various signals and their cognate receptors is required for the efficient symbiosis, its emergence most likely required coevolution of plants and bacteria.<ref>PMID:19485766</ref><ref>PMID: 11732607</ref> One of the bacterial nodulating symbionts is Bradyrhizobium japonicum WM9, which is involved in a partnership with lupine and serradella legumes.<ref>PMID: 14533715</ref> | The endosymbiotic relationship between nitrogen-fixing rhizobial bacteria and certain plants (legumes) is of the utmost importance for the nitrogen cycle in the biosphere and hence an object of intense study by specialists from various areas of biology. What is more, although the use of artificial nitrogen-containing fertilizers made it possible to bypass the strict dependence on this process, its understanding is still crucial for the efficient agriculture. Biological nitrogen fixation requires [[nitrogenase]], an enzyme present in, among others, rhizobial bacteria but absent in plants. The rhizobia are a diverse range of soil bacteria. It is thought that after the symbiotic capabilities were first acquired by some of them, they spread by means of horizontal transfer of a plasmid or genomic island containing genes important for the process. The symbiotic relationship between the two symbionts depends on the formation of invasion structures (nodules) by the host, allowing bacteria to enter the plant root, colonize a specific type of cells and be transformed into bacteroids which perform nitrogen fixation. As complementarity between various signals and their cognate receptors is required for the efficient symbiosis, its emergence most likely required coevolution of plants and bacteria.<ref>PMID:19485766</ref><ref>PMID: 11732607</ref> One of the bacterial nodulating symbionts is Bradyrhizobium japonicum WM9, which is involved in a partnership with lupine and serradella legumes.<ref>PMID: 14533715</ref> | ||
===Chemical signals=== | ===Chemical signals=== | ||
The very first stage of this process is an exchange of chemical signals between the symbionts. On sensing a flavonoid compound released by the plant, the bacteria produce a signalling molecule known as Nod factor, which is a lipochitooligosaccharide derivative. This molecule in turn induces nodule formation by the plant.<ref>PMID: 18444906</ref><ref>PMID: 17632573</ref><ref>PMID: 1444265</ref> Many types of flavonoids and Nod factors are known and which ones are present influences the specificity of the interaction. It must be mentioned that while these two molecules are important signals and specificity determinants, there are numerous others.<ref>PMID: 20070373</ref><ref>PMID: 18616593</ref> | The very first stage of this process is an exchange of chemical signals between the symbionts. On sensing a flavonoid compound released by the plant, the bacteria produce a signalling molecule known as Nod factor, which is a lipochitooligosaccharide derivative. This molecule in turn induces nodule formation by the plant.<ref>PMID: 18444906</ref><ref>PMID: 17632573</ref><ref>PMID: 1444265</ref> Many types of flavonoids and Nod factors are known and which ones are present influences the specificity of the interaction. It must be mentioned that while these two molecules are important signals and specificity determinants, there are numerous others.<ref>PMID: 20070373</ref><ref>PMID: 18616593</ref> | ||
