Identification of critical residues of the serotype modifying O-acetyltransferase of Shigella flexneri.
Identification of critical residues of the serotype modifying O-acetyltransferase of Shigella flexneri.
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DOI：
10.1186/1471-2091-13-13
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发表时间：
2012-07-15
期刊：
影响因子：
--
通讯作者：
Verma NK
中科院分区：
文献类型：
--
作者：
Thanweer F;Verma NK
福氏志贺菌13个血清型（S.福氏杆菌），所有这些细菌都能引起细菌性痢疾或志贺氏菌病。随着较新的S.在福氏血清型中，有效疫苗的开发变得更具挑战性。导致血清型多样性产生的因素之一是LPS O-抗原修饰的整合膜蛋白，称为O-乙酰转移酶或Oac。Oac通过将乙酰基添加到特定的O-抗原糖上来发挥作用，从而改变亲本S的抗原特征。福氏菌株Oac是一种膜蛋白，由疏水性和亲水性组分组成。Oac与几种已知和预测的乙酰转移酶具有同源性，其中大部分同源性存在于N-末端跨膜（TM）区域。本研究对S. flexneri Oac进行诱变，目的是鉴定Oac功能所必需的氨基酸残基。我们先前在Oac的胞质环3中鉴定了三个关键的三肽-R73、R75和R76。重新建立，这些生物碱是至关重要的，在这项研究中，我们建议的催化作用，R73和R75和R76在O-乙酰化的结构作用。还发现在TM片段中发现的丝氨酸-甘氨酸基序（SG 52-53、GS 138-139和SYG 274-276）、苯丙氨酸-脯氨酸基序（FP 78-79和FPV 282-84）和色氨酸-苏氨酸基序（WT 141 -142）以及在亲水环中发现的残基RK 110-111、GR 269-270和D333对Oac功能至关重要。通过研究突变对Oac功能和组装的影响，深入了解Oac中所选氨基酸可能发挥的作用。跨膜丝氨酸-甘氨酸基序和亲水残基（RK 110-111、GR 269-270和D333）显示对Oac组装具有影响，这表明这些基序的结构作用。苯丙氨酸-脯氨酸和色氨酸-苏氨酸基序影响Oac功能，这可能表明这些氨基酸的催化作用。
Thirteen serotypes of Shigella flexneri (S. flexneri) have been recognised, all of which are capable of causing bacillary dysentery or shigellosis. With the emergence of the newer S. flexneri serotypes, the development of an effective vaccine has only become more challenging. One of the factors responsible for the generation of serotype diversity is an LPS O-antigen modifying, integral membrane protein known as O-acetyltransferase or Oac. Oac functions by adding an acetyl group to a specific O-antigen sugar, thus changing the antigenic signature of the parent S. flexneri strain. Oac is a membrane protein, consisting of hydrophobic and hydrophilic components. Oac bears homology to several known and predicted acetyltransferases with most homology existing in the N-terminal transmembrane (TM) regions. In this study, the conserved motifs in the TM regions and in hydrophilic loops of S. flexneri Oac were targeted for mutagenesis with the aim of identifying the amino acid residues essential for the function of Oac. We previously identified three critical arginines–R73, R75 and R76 in the cytoplasmic loop 3 of Oac. Re-establishing that these arginines are critical, in this study we suggest a catalytic role for R73 and a structural role for R75 and R76 in O-acetylation. Serine-glycine motifs (SG 52–53, GS 138–139 and SYG 274–276), phenylalanine-proline motifs (FP 78–79 and FPV 282–84) and a tryptophan-threonine motif (WT141-142) found in TM segments and residues RK 110–111, GR 269–270 and D333 found in hydrophilic loops were also found to be critical to Oac function. By studying the effect of the mutations on Oac’s function and assembly, an insight into the possible roles played by the chosen amino acids in Oac was gained. The transmembrane serine-glycine motifs and hydrophilic residues (RK 110–111, GR 269–270 and D333) were shown to have an affect on Oac assembly which suggests a structural role for these motifs. The phenylalanine-proline and the tryptophan-threonine motifs affect Oac function which could suggest a catalytic role for these amino acids.
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影响因子：
2.9
作者：
Loladze, VV;Ibarra-Molero, B;Makhatadze, GI
通讯作者：
Makhatadze, GI
影响因子：
4.1
作者：
Goodfellow, GH;Dupret, JM;Grant, DM
通讯作者：
Grant, DM
影响因子：
4.8
作者：
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影响因子：
4.8
作者：
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通讯作者：
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影响因子：
3.2
作者：
HITCHCOCK, PJ;BROWN, TM
通讯作者：
BROWN, TM