Manganese is required for oxidative metabolism in unstressed Bradyrhizobium japonicum cells.
Manganese is required for oxidative metabolism in unstressed Bradyrhizobium japonicum cells.
复制标题
DOI：
10.1111/j.1365-2958.2012.08057.x
复制
发表时间：
2012-05
影响因子：
3.6
通讯作者：
O'Brian MR
中科院分区：
文献类型：
--
作者：
Hohle TH;O'Brian MR
最近对Mn2+转运突变体的研究表明，锰对某些细菌的非胁迫生长是必需的，但对其他细菌来说，锰主要是诱导胁迫反应所必需的。一个缺失高亲和力Mn2+转运体基因mntH的缓生根瘤菌突变体在锰限制条件下表现出严重的生长表型，表明在非胁迫条件下生长需要金属。在锰限制条件下，我们发现mntH菌株的超氧化物歧化酶和糖酵解酶丙酮酸激酶活性不足。基于pykM突变体活性缺失、丙酮酸恢复生长表型以及纯化重组pykM的丙酮酸激酶活性，我们确定pykM是唯一的丙酮酸激酶编码基因。PykM的不同寻常之处在于它需要Mn2+而不是Mg2+才能获得高活性，并且果糖1,6-二磷酸和AMP都不是正变构效应物。mnth依赖的超氧化物歧化酶由sodM编码，sodM是在非胁迫生长条件下唯一表达的超氧化物歧化酶编码基因。与pykM sodM双突变体相比，mntH突变体在限制锰的丙酮酸盐条件下生长得更慢，这意味着额外的锰依赖过程。这些发现暗示了锰在日本芽孢杆菌非应激氧化代谢的关键步骤中的作用。
Recent studies of Mn2+ transport mutants indicate that manganese is essential for unstressed growth in some bacterial species, but is required primarily for induced stress responses in others. A Bradyrhizobium japonicum mutant defective in the high affinity Mn2+ transporter gene mntH has a severe growth phenotype under manganese limitation, suggesting a requirement for the metal under unstressed growth. Here, we found that activities of superoxide dismutase and the glycolytic enzyme pyruvate kinase were deficient in an mntH strain grown under manganese limitation. We identified pykM as the only pyruvate kinase-encoding gene based on deficiency in activity of a pykM mutant, rescue of the growth phenotype with pyruvate, and pyruvate kinase activity of purified recombinant PykM. PykM is unusual in that it required Mn2+ rather than Mg2+ for high activity, and that neither fructose 1,6-bisphosphate nor AMP was a positive allosteric effector. The mntH-dependent superoxide dismutase is encoded by sodM, the only expressed superoxide dismutase-encoding gene under unstressed growth conditions. An mntH mutant grew more slowly on pyruvate under manganese-limited conditions than did a pykM sodM double mutant, implying additional manganese-dependent processes. The findings implicate roles for manganese in key steps in unstressed oxidative metabolism in B. japonicum.
登录
查看更多内容
影响因子：
3.6
作者：
Martin JE;Imlay JA
通讯作者：
Imlay JA
影响因子：
3.6
作者：
Hohle TH;O'Brian MR
通讯作者：
O'Brian MR
影响因子：
3.6
作者：
Anjem A;Varghese S;Imlay JA
通讯作者：
Imlay JA
影响因子：
4.1
作者：
Kaneko, T;Nakamura, Y;Tabata, S
通讯作者：
Tabata, S
影响因子：
3.6
作者：
Makui, H;Roig, E;Cellier, MFM
通讯作者：
Cellier, MFM