Lysine and threonine biosynthesis from aspartate contributes to Staphylococcus aureus growth in calf serum.
Lysine and threonine biosynthesis from aspartate contributes to Staphylococcus aureus growth in calf serum.
复制标题
天冬氨酸的赖氨酸和苏氨酸生物合成有助于小牛血清中金黄色葡萄球菌的生长。
DOI：
10.1128/aem.01399-16
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发表时间：
2016
影响因子：
4.4
通讯作者：
H.
中科院分区：
文献类型：
--
作者：
Oogai;Y.;Yamaguchi;M.;Kawada-Matsuo;M.;Sumitomo;T.;Kawabata;S.;Komatsuzawa;H.
金黄色葡萄球菌是一种人类病原体，S.金黄色葡萄球菌菌血症可在人类中引起严重的问题。为了鉴定细菌在小牛血清（CS）中生长所需的基因，构建了S。分析具有随机插入的转座子的金黄色葡萄球菌突变体在CS中的生长，与野生型（WT）相比，天冬氨酸半醛脱氢酶（asd）失活的突变体在CS中表现出显著降低的生长。该突变体还表现出显着降低的生长在培养基中，模仿CS中的氨基酸和葡萄糖的浓度。天冬氨酸脱氢酶是从天冬氨酸合成赖氨酸、蛋氨酸和苏氨酸的必需酶。我们构建了赖氨酸（lysA）、甲硫氨酸（metE）和苏氨酸（thrC）生物合成基因的失活突变体，发现失活的lysA和thrC突变体在CS中的生长显著低于WT，但metE突变体的生长与WT相似。在CS中添加100 μg/ml赖氨酸和苏氨酸可恢复突变体的生长。这些结果表明S.金黄色葡萄球菌需要赖氨酸和苏氨酸生物合成以在CS中生长。另一方面，与WT相比，asd-、lysA-、metE-和thrC-失活突变体在小鼠血清中表现出显著降低的生长。在小鼠菌血症实验中，与WT感染相比，asd-、lysA-、metE-和thrC-失活突变体表现出减弱的毒力。总之，我们的研究结果表明，de novoaspartate家族氨基酸，特别是赖氨酸和苏氨酸的生物合成，是重要的葡萄球菌血流infection. IMPORTANCE研究细菌在血液中的生长是重要的，了解其在宿主的致病性。金黄色葡萄球菌有时会引起菌血症或败血症。然而，S.金黄色葡萄球菌在血液中的生长还不清楚。本研究利用含有2，914个转座子插入突变体的S.金黄色葡萄球菌MW 2菌株，我们确定了负责CS中细菌生长的因素。我们发现赖氨酸和苏氨酸生物合成基因的失活导致CS生长不足。然而，这些基因的失活并不影响S。金黄色葡萄球菌在普通培养基中生长。由于CS中的氨基酸浓度较低，我们的研究结果表明赖氨酸和苏氨酸的生物合成对S.金黄色葡萄球菌。我们的发现为S.金黄色葡萄球菌在宿主中的适应和了解菌血症的发病机制。
Staphylococcus aureus is a human pathogen, and S. aureus bacteremia can cause serious problems in humans. To identify the genes required for bacterial growth in calf serum (CS), a library of S. aureus mutants with randomly inserted transposons were analyzed for growth in CS, and the aspartate semialdehyde dehydrogenase (asd)-inactivated mutant exhibited significantly reduced growth in CS compared with the wild type (WT). The mutant also exhibited significantly reduced growth in medium, mimicking the concentrations of amino acids and glucose in CS. Asd is an essential enzyme for the biosynthesis of lysine, methionine, and threonine from aspartate. We constructed inactivated mutants of the genes for lysine (lysA), methionine (metE), and threonine (thrC) biosynthesis and found that the inactivated mutants oflysAandthrCexhibited significantly lower growth in CS than the WT, but the growth of themetEmutant was similar to that of the WT. The reduced growth of theasdmutant was recovered by addition of 100 μg/ml lysine and threonine in CS. These results suggest that S. aureus requires lysine and threonine biosynthesis to grow in CS. On the other hand, theasd-,lysA-,metE-, andthrC-inactivated mutants exhibited significantly reduced growth in mouse serum compared with the WT. In mouse bacteremia experiments, theasd-,lysA-,metE-, andthrC-inactivated mutants exhibited attenuated virulence compared with WT infection. In conclusion, our results suggest that the biosynthesis ofde novoaspartate family amino acids, especially lysine and threonine, is important for staphylococcal bloodstream infection.IMPORTANCEStudying the growth of bacteria in blood is important for understanding its pathogenicity in the host. Staphylococcus aureus sometimes causes bacteremia or sepsis. However, the factors responsible for S. aureus growth in the blood are not well understood. In this study, using a library of 2,914 transposon-insertional mutants in the S. aureus MW2 strain, we identified the factors responsible for bacterial growth in CS. We found that inactivation of the lysine and threonine biosynthesis genes led to deficient growth in CS. However, the inactivation of these genes did not affect S. aureus growth in general medium. Because the concentration of amino acids in CS is low compared to that in general bacterial medium, our results suggest that lysine and threonine biosynthesis is important for the growth of S. aureus in CS. Our findings provide new insights for S. aureus adaptation in the host and for understanding the pathogenesis of bacteremia.