Amino-terminal maturation of the Bordetella pertussis filamentous haemagglutinin
Amino-terminal maturation of the Bordetella pertussis filamentous haemagglutinin
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DOI：
10.1046/j.1365-2958.1996.349883.x
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发表时间：
1996-01-01
影响因子：
3.6
通讯作者：
Locht, C
中科院分区：
文献类型：
--
作者：
JacobDubuisson, F;Buisine, C;Locht, C
220 kDa丝状血凝素（FHA）是百日咳杆菌的主要黏附素，由一种称为FHA的大前体产生。虽然部分与表面相关，但它也非常有效地分泌到细胞外环境中。其分泌依赖于外膜辅助蛋白FhaC。FHA的一个80 kDa的n端衍生物Fha44也可以非常有效地以fhac依赖的方式分泌，这表明所有必要的分泌信号都位于FhaB的n端区域。FHA衍生物的预测尺寸和表观尺寸的比较，以及细胞相关和分泌的FHA多肽的免疫印迹分析表明，FhaB通过8-9 kDa片段的切割经历n端成熟。然而，翻译lacZ和phoA融合物的表型分析表明，该片段不作为典型的信号肽。Fha44编码基因与fhaC的共表达也不允许在大肠杆菌中分泌Fha44。然而，当OmpA信号肽融合到Fha44的n端时，可以观察到高水平的分泌。不管OmpA信号肽-Fha44的融合点是什么，大肠杆菌分泌的Fha44与百日咳杆菌分泌的Fha44具有相同的M(r)，这表明n端蛋白水解成熟不需要百日咳杆菌特异性因子。与FHA类似，百日咳B.分泌的Fha44在其n端含有一个尚未表征的修饰。这种修饰没有发生在大肠杆菌中，因此不需要分泌。对大肠杆菌分泌的Fha44的n端进行了测定，发现其对应于FhaB第一个框架内蛋氨酸后的第72个残基。n端修饰也被发现不需要血液凝集或与硫酸糖缀合物相互作用。
The 220 kDa filamentous haemagglutinin (FHA) is a major adhesin of Bordetella pertussis and is produced from a large precursor designated FhaB. Although partly surface associated, it is also very efficiently secreted into the extracellular milieu. Its secretion depends on the outer membrane accessory protein FhaC. An 80 kDa N-terminal derivative of FHA, named Fha44, can also be very efficiently secreted in a FhaC-dependent manner, indicating that all necessary secretion signals are localized in the N-terminal region of FhaB. A comparison of predicted and apparent sizes of FHA derivatives, in addition to immunoblot analyses of cell-associated and secreted FHA polypeptides, indicated that FhaB undergoes N-terminal maturation by the cleavage of an 8-9 kDa segment. However, phenotypic analyses of translational lacZ and phoA fusions showed that this segment does not function as a typical signal peptide. Co-expression of the Fha44-encoding gene with fhaC also did not allow for secretion of Fha44 in Escherichia coli. High levels of secretion could, however, be observed when the OmpA signal peptide was fused to the N-terminal end of Fha44. Regardless of the OmpA signal peptide-Fha44 fusion point, the E. coli-secreted Fha44 had the same M(r) as that secreted by B. pertussis, indicating that the N-terminal proteolytic maturation does not require a B. pertussis-specific factor. Similar to FHA, the B. pertussis-secreted Fha44 contains an as yet uncharacterized modification at its N-terminus. This modification did not occur in E. coli and is therefore not required for secretion. The N-terminus of Fha44 secreted by E. coli was determined and found to correspond to the 72nd residue after the first in-frame methionine of FhaB. The N-terminal modification was also found not to be required for haemagglutination or interaction with sulphated glycoconjugates.