Kolenbrander P E, Andersen R N, Ganeshkumar N
Laboratory of Microbial Ecology, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892.
Infect Immun. 1994 Oct;62(10):4469-80. doi: 10.1128/iai.62.10.4469-4480.1994.
Human oral viridans group streptococci that coaggregate with Actinomyces naeslundii PK606 express surface proteins related to ScaA, the coaggregation-mediating adhesin of Streptococcus gordonii PK488 (R. N. Andersen, N. Ganeshkumar, and P. E. Kolenbrander, Infect. Immun. 61:981-987, 1993). The nucleotide sequence of the 6,125-bp EcoRI insert of pRA1, containing scaA, the gene encoding ScaA, was determined. Six open reading frames (ORFs) were identified. The orientation of four ORFs, two upstream (ORF 1 and ORF 2) and one downstream (ORF 4) of scaA (ORF 3), indicated transcription in one direction, whereas ORF 5 and ORF 6 were transcribed divergently. Computer analysis of the deduced amino acid sequences identified a consensus binding site for ATP (GxxGxGKS) in the putative 28,054-Da protein encoded by ORF 1. ORF 2 potentially encoded a hydrophobic protein of 29,705 Da with six potential membrane-spanning regions. ScaA was 310 amino acids, 34,787 Da, and contained the lipoprotein consensus sequence LxxC, also reported for the ScaA-related proteins SsaB, FimA, and PsaA from Streptococcus sanguis 12, Streptococcus parasanguis FW213, and Streptococcus pneumoniae R36A, respectively. ORF 4 potentially encoded a 163-amino-acid protein of 17,912 Da, which was nearly identical to the downstream adjacent gene products of ssaB, fimA, and psaA. No significant homology with other proteins was found with the putative ORF 5 gene product, a 229-amino-acid protein of 25,107 Da. ORF 6 was incomplete and encoded a protein larger than 564 amino acids. This putative protein had a consensus Zn2+ binding motif, HExxH, found among bacterial thermolysins and mammalian neutral endopeptidases and was 40% identical to a homologous 210-amino-acid region of human enkephalinase. The genetic organization of ORFs 1, 2, and 3 was similar to those of the bacterial periplasmic-binding protein-dependent transport systems of gram-negative bacteria and binding-lipoprotein-dependent transport systems of gram-positive bacteria, and these genes appeared to encode ABC (ATP-binding cassette) proteins. This report describes a cell-to-cell adherence function associated with an ATP-binding cassette.
与内氏放线菌PK606共聚集的人类口腔草绿色链球菌群表达与ScaA相关的表面蛋白，ScaA是戈登链球菌PK488的共聚集介导黏附素（R. N. 安德森、N. 加内什库马尔和P. E. 科伦布兰德，《感染与免疫》61:981 - 987, 1993年）。测定了含有编码ScaA的基因scaA的pRA1的6125 bp EcoRI插入片段的核苷酸序列。鉴定出六个开放阅读框（ORF）。scaA（ORF 3）上游的两个ORF（ORF 1和ORF 2）以及下游的一个ORF（ORF 4）的方向表明转录方向相同，而ORF 5和ORF 6转录方向相反。对推导的氨基酸序列进行计算机分析，在ORF 1编码的假定28054 Da蛋白质中鉴定出一个ATP的共有结合位点（GxxGxGKS）。ORF 2可能编码一个29705 Da的疏水蛋白，有六个潜在的跨膜区域。ScaA由310个氨基酸组成，分子量为34787 Da，包含脂蛋白共有序列LxxC，分别也报道于血链球菌12、副血链球菌FW213和肺炎链球菌R36A的与ScaA相关的蛋白SsaB、FimA和PsaA中。ORF 4可能编码一个163个氨基酸、分子量为17912 Da的蛋白质，它与ssaB、fimA和psaA的下游相邻基因产物几乎相同。假定的ORF 5基因产物是一个229个氨基酸、分子量为25107 Da的蛋白质，与其他蛋白质没有显著同源性。ORF 6不完整，编码一个大于564个氨基酸的蛋白质。这个假定的蛋白质有一个在细菌嗜热菌蛋白酶和哺乳动物中性内肽酶中发现的共有Zn2 +结合基序HExxH，并且与人类脑啡肽酶的一个同源210个氨基酸区域有40%的同一性。ORF 1、2和3的基因组织与革兰氏阴性菌的细菌周质结合蛋白依赖性转运系统以及革兰氏阳性菌的结合脂蛋白依赖性转运系统相似，并且这些基因似乎编码ABC（ATP结合盒）蛋白。本报告描述了一种与ATP结合盒相关的细胞间黏附功能。
