Processing Is Required for a Fully Functional Protein P30 in Mycoplasma pneumoniae Gliding and Cytadherence
Processing Is Required for a Fully Functional Protein P30 in Mycoplasma pneumoniae Gliding and Cytadherence
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DOI：
10.1128/jb.00104-11
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发表时间：
2011-10-01
影响因子：
3.2
通讯作者：
Krause, Duncan C.
中科院分区：
文献类型：
--
作者：
Chang, How-Yi;Prince, Oliver A.;Krause, Duncan C.
无细胞壁的原核生物肺炎支原体导致人类支气管炎和非典型肺炎。支原体附着于宿主呼吸道上皮是定植所必需的，并且主要由分化的终末细胞器介导。P30是位于终末细胞器远端的膜蛋白。与野生型相比，P30无效突变体II-3不能附着于宿主细胞并且不运动，并且具有分支细胞形态，表明P30在M中的重要作用。肺炎生物学预测P30具有N-末端信号序列，但这种基序的存在尚未被实验证实。在目前的研究中，我们分析了P30衍生物的表位标签工程在不同的位置，以证明翻译后加工发生在P30。几个潜在的切割位点预测在计算机上进行了检查，并创建了一个加工缺陷的突变体，以进一步探索P30成熟。我们的结果表明，信号肽切割发生在残基52和53之间，以产生成熟的P30。加工缺陷的突变体表现出降低滑行速度和cytadherence，表明加工是需要的P30的功能完全成熟。我们推测，P30加工可能会引发细胞外结构域的构象变化或暴露在胞质结构域上的结合位点，以允许与结合伴侣的相互作用作为功能成熟的一部分。
The cell wall-less prokaryote Mycoplasma pneumoniae causes bronchitis and atypical pneumonia in humans. Mycoplasma attachment to the host respiratory epithelium is required for colonization and mediated largely by a differentiated terminal organelle. P30 is an integral membrane protein located at the distal end of the terminal organelle. The P30 null mutant II-3 is unable to attach to host cells and nonmotile and has a branched cellular morphology compared to the wild type, indicating an important role for P30 in M. pneumoniae biology. P30 is predicted to have an N-terminal signal sequence, but the presence of such a motif has not been confirmed experimentally. In the current study we analyzed P30 derivatives having epitope tags engineered at various locations to demonstrate that posttranslational processing occurred in P30. Several potential cleavage sites predicted in silico were examined, and a processing-defective mutant was created to explore P30 maturation further. Our results suggested that signal peptide cleavage occurs between residues 52 and 53 to yield mature P30. The processing-defective mutant exhibited reduced gliding velocity and cytadherence, indicating that processing is required for fully functional maturation of P30. We speculate that P30 processing may trigger a conformational change in the extracellular domain or expose a binding site on the cytoplasmic domain to allow interaction with a binding partner as a part of functional maturation.