Harriott O T, Huber R, Stetter K O, Betts P W, Noll K M
Department of Molecular and Cell Biology, University of Connecticut, Storrs 06269.
J Bacteriol. 1994 May;176(9):2759-62. doi: 10.1128/jb.176.9.2759-2762.1994.
An 846-bp cryptic plasmid has been discovered in the hyperthermophilic bacterium Thermotoga sp. strain RQ7. This is the first plasmid described for an organism from this ancient bacterial lineage and the smallest plasmid described to date for any organism. Nucleotide sequencing revealed a single open reading frame possibly encoding a 25,460-Da basic protein (212 amino acids). Upstream of the putative promoter lie five 11-bp direct repeats, each separated by 1 to 4 bp, while between the promoter and the open reading frame lies an 11-bp palindromic sequence. Its mode of replication is unknown, but its sequence bears similarities to those of plasmids which replicate by a rolling-circle mechanism.
在嗜热细菌嗜热栖热菌（Thermotoga sp.）菌株RQ7中发现了一个846碱基对的隐蔽质粒。这是首次为来自这个古老细菌谱系的生物体描述的质粒，也是迄今为止为任何生物体描述的最小质粒。核苷酸测序揭示了一个单一的开放阅读框，可能编码一种25460道尔顿的碱性蛋白（212个氨基酸）。在推定的启动子上游有五个11碱基对的直接重复序列，每个重复序列相隔1至4个碱基对，而在启动子和开放阅读框之间有一个11碱基对的回文序列。其复制模式尚不清楚，但其序列与通过滚环机制复制的质粒序列有相似之处。
