Chromosomal DNA deletions explain phenotypic characteristics of two antigenic variants, phase II and RSA 514 (crazy), of the Coxiella burnetii Nine Mile strain
Chromosomal DNA deletions explain phenotypic characteristics of two antigenic variants, phase II and RSA 514 (crazy), of the Coxiella burnetii Nine Mile strain
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DOI：
10.1128/iai.70.12.6726-2733.2002
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发表时间：
2002-12-01
影响因子：
3.1
通讯作者：
Thompson, HA
中科院分区：
文献类型：
--
作者：
Hoover, TA;Culp, DW;Thompson, HA
通过胚胎卵反复传代后，贝氏柯克斯体九里株表现出抗原性变异，丧失毒力特征，并转变为截短的脂多糖（LPS）结构。在两个独立衍生的菌株中，九里II期和RSA 514，这些表型变化伴随着一个大的染色体缺失（M。H.伏特加和J. C。威廉姆斯，《微生物遗传学杂志》。132：2587-2594，1986）。在这里报道的工作中，使用从野生型菌株制备的粘粒库的额外筛选来绘制两种突变菌株的缺失末端，并积累包含两种缺失的所有DNA片段。然后对相应的DNA进行测序和注释。Nine Mile II期缺失完全嵌套在RSA 514菌株的缺失内。基本的比对和同源性研究表明，一大群的LPS生物合成基因，安排在一个明显的O-抗原簇，在这两种变体中被删除。数据库同源性鉴定，特别是甘露糖途径基因和编码糖甲基化酶和核苷酸糖差向异构酶-淀粉酶蛋白的基因。在缺失区域中鉴定了向核心寡糖添加糖单元以合成稀有糖6-脱氧-3-C-甲基古洛糖（病毒糖）的候选基因。重复，冗余，旁系同源基因，和两个区域内的G+C含量降低被发现的缺失。
After repeated passages through embyronated eggs, the Nine Mile strain of Coxiella burnetii exhibits antigenic variation, a loss of virulence characteristics, and transition to a truncated lipopolysaccharide (LPS) structure. In two independently derived strains, Nine Mile phase II and RSA 514, these phenotypic changes were accompanied by a large chromosomal deletion (M. H. Vodkin and J. C. Williams, J. Gen. Microbiol. 132:2587-2594, 1986). In the work reported here, additional screening of a cosmid bank prepared from the wild-type strain was used to map the deletion termini of both mutant strains and to accumulate all the segments of DNA that comprise the two deletions. The corresponding DNAs were then sequenced and annotated. The Nine Mile phase II deletion was completely nested within the deletion of the RSA 514 strain. Basic alignment and homology studies indicated that a large group of LPS biosynthetic genes, arranged in an apparent O-antigen cluster, was deleted in both variants. Database homologies identified, in particular, mannose pathway genes and genes encoding sugar methylases and nucleotide sugar epimerase-dehydratase proteins. Candidate genes for addition of sugar units to the core oligosaccharide for synthesis of the rare sugar 6-deoxy-3-C-methylgulose (virenose) were identified in the deleted region. Repeats, redundancies, paralogous genes, and two regions with reduced G+C contents were found within the deletions.