Division of Periodontology, Diagnostic Sciences and Dental Hygiene, Herman Ostrow School of Dentistry of the University of Southern California, Los Angeles, CA, USA.
BMC Genomics. 2010 Sep 8;11:489. doi: 10.1186/1471-2164-11-489.
Bacterial phenotype may be profoundly affected by the physical arrangement of their genes in the genome. The Gram-negative species Aggregatibacter actinomycetemcomitans is a major etiologic agent of human periodontitis. Individual clonal types of A. actinomycetemcomitans may exhibit variable virulence and different patterns of disease association. This study examined the genome arrangement of A. actinomycetemcomitans using the genome sequences of serotypes a-c strains. The genome alignment and rearrangement were analyzed by the MAUVE and the GRIMM algorithms. The distribution patterns of genes along the leading/lagging strands were investigated. The occurrence and the location of repeat sequences relative to the genome rearrangement breakpoints were also determined.
The genome arrangement of the serotype a strain D7S-1 is markedly different from the serotype b strain HK1651 or the serotype c strain D11S-1. Specific genome arrangements appear to be conserved among strains of the same serotypes. The reversal distance between D7S-1 and HK1651 by GRIMM analysis is also higher than the within-species comparisons of 7 randomly selected bacterial species. The locations of the orthologous genes are largely preserved between HK1651 and D11S-1 but not between D7S-1 and HK1651 (or D11S-1), irrespective of whether the genes are categorized as essential/nonessential or highly/nonhighly expressed. However, genome rearrangement did not disrupt the operons of the A. actinomycetemcomitans strains. A higher proportion of the genome in strain D7S-1 is occupied by repeat sequences than in strains HK1651 or D11S-1.
The results suggest a significant evolutionary divergence between serotype a strains and serotypes b/c strains of A. actinomycetemcomitans. The distinct patterns of genome arrangement may suggest phenotypic differences between serotype a and serotypes b/c strains.
细菌表型可能会受到基因组中基因物理排列的极大影响。革兰氏阴性物种伴放线放线杆菌是人类牙周炎的主要病原体。伴放线放线杆菌的个体克隆类型可能具有不同的毒力和不同的疾病关联模式。本研究使用血清型 a-c 菌株的基因组序列检查了伴放线放线杆菌的基因组排列。通过 MAUVE 和 GRIMM 算法分析基因组比对和重排。研究了基因沿前导/滞后链的分布模式。还确定了重复序列相对于基因组重排断点的出现和位置。
血清型 a 菌株 D7S-1 的基因组排列与血清型 b 菌株 HK1651 或血清型 c 菌株 D11S-1 明显不同。特定的基因组排列似乎在同一血清型的菌株中保持不变。通过 GRIMM 分析，D7S-1 和 HK1651 之间的反转距离也高于 7 个随机选择的细菌物种的种内比较。HK1651 和 D11S-1 之间的同源基因位置基本保持不变，但 D7S-1 和 HK1651（或 D11S-1）之间则不然，无论基因是否被归类为必需/非必需或高/非高表达。然而，基因组重排并未破坏伴放线放线杆菌菌株的操纵子。D7S-1 中的基因组有更高比例被重复序列占据，而在 HK1651 或 D11S-1 中则较少。
结果表明，血清型 a 菌株和伴放线放线杆菌血清型 b/c 菌株之间存在显著的进化分歧。基因组排列的不同模式可能表明血清型 a 和血清型 b/c 菌株之间存在表型差异。
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