Mattatall N R, Daines D A, Liu S L, Sanderson K E
Salmonella Genetic Stock Centre, Department of Biological Sciences, University of Calgary, Alberta, Canada.
J Bacteriol. 1996 Sep;178(17):5323-6. doi: 10.1128/jb.178.17.5323-5326.1996.
Salmonella typhi Ty2 rrl genes contain intervening sequences (IVSs) in helix-25 but not in helix-45 on the basis of observed 23S rRNA fragmentation caused by IVS excision. We have confirmed this and shown all seven IVSs to be identical by isolating genomic DNA fragments containing each of the seven rrl genes from S. typhi Ty2 by use of pulsed-field gel electrophoresis; each rrl gene was amplified by PCR in the helix-25 and helix-45 regions and cycle sequenced. Thirty independent wild-type S. typhi strains, tested by genomic PCR and DraI restriction, also have seven rrl genes with helix-25 IVSs and no helix-45 IVSs. We propose that IVS homogeneity in S. typhi occurs because gene conversion drives IVS sequence maintenance and because adaptation to human hosts results in limited clonal diversity.
基于观察到的由间隔序列（IVS）切除导致的23S rRNA片段化，伤寒沙门氏菌Ty2的rrl基因在螺旋25中含有间隔序列，但在螺旋45中没有。我们已经证实了这一点，并通过使用脉冲场凝胶电泳从伤寒沙门氏菌Ty2中分离出包含七个rrl基因中每个基因的基因组DNA片段，表明所有七个IVS都是相同的；每个rrl基因在螺旋25和螺旋45区域通过PCR进行扩增并循环测序。通过基因组PCR和DraI酶切检测的30个独立野生型伤寒沙门氏菌菌株也有七个带有螺旋25 IVS且没有螺旋45 IVS的rrl基因。我们提出，伤寒沙门氏菌中IVS的同质性出现是因为基因转换驱动IVS序列维持，并且因为对人类宿主的适应导致有限的克隆多样性。
