van Heerden Henriette, Collins Nicola E, Brayton Kelly A, Rademeyer Celia, Allsopp Basil A
Department of Chemistry and Biochemistry, Rand Afrikaans University, P.O. Box 524, Auckland Park 2006, South Africa.
Gene. 2004 Apr 14;330:159-68. doi: 10.1016/j.gene.2004.01.020.
Ehrlichia ruminantium is a tick-transmitted rickettsial pathogen, which causes heartwater or cowdriosis in wild and domestic ruminants. A dominant antibody response of animals infected with E. ruminantium is directed against the outer membrane protein MAP1 (major antigenic protein 1). Part of the locus containing map1 has been characterized and consists of four map1 paralogs, designated map1-2, map1-1, map1 and map1+1, indicating that map1 is encoded by a multigene family. The purpose of this study was to determine the total number of map1 paralogs and their transcriptional activities. Using genome walking and data from an ongoing E. ruminantium genome sequencing project at the Onderstepoort Veterinary Institute, we found 16 paralogs of the map1 gene tandemly arranged in a 25 kb region of the E. ruminantium genome. The map1 multigene family is downstream of a hypothetical transcriptional regulator gene and upstream of the secA gene. Thirteen paralogs at the 5' end of the 25-kb locus were connected by short intergenic spaces (ranging from 0 to 42 bp) and the remaining three paralogs at the 3' end were connected by longer intergenic spaces (ranging from 375 to 1612 bp). All 16 map1 paralogs were transcriptionally active in E. ruminantium grown in endothelial cells and paralogs with short intergenic spaces were co-transcribed with their adjacent genes.
反刍动物埃立克体是一种通过蜱传播的立克次氏体病原体，可在野生和家养反刍动物中引起心水病或考德里氏体病。感染反刍动物埃立克体的动物的主要抗体反应针对外膜蛋白MAP1（主要抗原蛋白1）。包含map1的部分基因座已被鉴定，由四个map1旁系同源物组成，分别命名为map1-2、map1-1、map1和map1+1，这表明map1由一个多基因家族编码。本研究的目的是确定map1旁系同源物的总数及其转录活性。利用基因组步移技术和翁德斯特普特兽医研究所正在进行的反刍动物埃立克体基因组测序项目的数据，我们发现map1基因的16个旁系同源物串联排列在反刍动物埃立克体基因组的一个25 kb区域内。map1多基因家族位于一个假定的转录调节基因的下游和secA基因的上游。25 kb基因座5'端的13个旁系同源物由短的基因间隔（0至42 bp）连接，3'端的其余三个旁系同源物由较长的基因间隔（375至1612 bp）连接。所有16个map1旁系同源物在在内皮细胞中生长的反刍动物埃立克体中均具有转录活性，并且基因间隔短的旁系同源物与其相邻基因共同转录。
