Purification and characterization of an extracellular peptide factor that affects two different developmental pathways in Bacillus subtilis
Purification and characterization of an extracellular peptide factor that affects two different developmental pathways in Bacillus subtilis
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DOI：
10.1101/gad.10.16.2014
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发表时间：
1996-08-15
影响因子：
10.5
通讯作者：
Grossman, AD
中科院分区：
文献类型：
--
作者：
Solomon, JM;Lazazzera, BA;Grossman, AD
我们纯化并表征了一种细胞外肽因子，该因子可作为枯草芽孢杆菌能力发育和孢子形成的细胞密度信号。这种能力和孢子形成刺激因子 (CSF) 是根据其在低细胞密度下刺激细胞中 srfA (comS) 表达的能力从条件培养基（培养上清液）中纯化的。 CSF 是一种 5 个氨基酸肽，glu-arg-gly-met-thr (ERGMT)，即 phrC 编码的 40 个氨基酸肽的羧基端 5 个氨基酸。 phrC 无效突变体中未产生可检测到的 CSF。化学合成的 CSF (ERGMT) 的活性与从培养物上清液中纯化的 CSF 的活性几乎没有区别。在相对较低的浓度（1-10 nM）下，CSP 刺激 srfA 的表达，而高浓度的 CSF 则刺激低细胞密度的细胞形成孢子的能力。 CSF 刺激 srfA 表达需要 spo0K（转运蛋白 ATP 结合盒家族的成员）编码的寡肽通透酶，以及 rapC（紧邻 phrC 上游的基因）编码的磷酸酶。 RapC被发现是srfA表达的负调节因子，表明RapC的靶标是comA编码的转录因子。我们认为 CSF 通过 Spo0K 寡肽通透酶转运到细胞中，并通过抑制（直接或间接）RapC 磷酸酶来刺激能力基因表达。
We have purified and characterized an extracellular peptide factor that serves as a cell density signal for both competence development and sporulation in Bacillus subtilis. This competence and sporulation stimulating factor (CSF) was purified from conditioned medium (culture supernatant) based on its ability to stimulate expression of srfA (comS) in cells at low cell density. CSF is a 5-amino-acid peptide, glu-arg-gly-met-thr (ERGMT), that is, the carboxy-terminal 5 amino acids of the 40-amino-acid peptide encoded by phrC. No detectable CSF was produced in a phrC null mutant. The activity of chemically synthesized CSF (ERGMT) was virtually indistinguishable from that of CSF that was purified from culture supernatants. At relatively low concentrations (1-10 nM), CSP stimulated expression of srfA, whereas high concentrations of CSF stimulated the ability of cells at low cell density to sporulate. Stimulation of srfA expression by CSF requires the oligopeptide permease encoded by spo0K, a member of the ATP-binding-cassette family of transporters, and the putative phosphatase encoded by rapC, the gene immediately upstream of phrC. RapC was found to be a negative regulator of srfA expression, suggesting that the target of RapC is the transcription factor encoded by comA. We propose that CSF is transported into the cell by the Spo0K oligopeptide permease and stimulates competence gene expression by inhibiting (either directly or indirectly) the RapC phosphatase.