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首页> 外文期刊>Journal of bacteriology >Identification of a nuclease and host restriction-modification in the unicellular, aerobic nitrogen-fixing cyanobacterium Cyanothece sp.
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Identification of a nuclease and host restriction-modification in the unicellular, aerobic nitrogen-fixing cyanobacterium Cyanothece sp.

机译：在单细胞，好氧固氮蓝藻蓝藻属中鉴定核酸酶并限制宿主的修饰。

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摘要

In the process of developing a gene transfer system for the marine, unicellular, nitrogen-fixing cyanobacterium Cyanothece sp. strain BH68K, two major restriction barriers have been identified. A cell wall-associated nuclease exhibited non-site-specific degradation of covalently closed circular and linear double-stranded DNA molecules, including Cyanothece sp. strain BH68K chromosomal DNA. The nuclease is easily released from intact cells by using water or buffer containing Triton X-100. Nuclease activity was undetectable in cell extracts prepared from water-washed cells. Comparison of the restriction endonuclease susceptibility of Cyanothece sp. strain BH68K DNA to that of Anabaena sp. strain PCC 7120 revealed that these organisms have a nearly identical pattern of restriction and therefore may contain similar systems for DNA methylation. Restriction by DpnI, MboI, and Sau3AI indicated the presence of adenine methylation. Cyanothece sp. strain BH68K cell extracts contain a type II restriction endonuclease, Csp68KI. The activity of Csp68KI was easily detected in cell extracts without extensive purification. Csp68KI is an isoschizomer of AvaII and recognizes the nucleotide sequence 5'-GG(A/T)CC-3'. Cleavage occurs between the guanosine nucleotides producing 3-bp 5' overhang ends.
机译：在开发用于海洋，单细胞，固氮蓝藻蓝藻属（Cyanothece sp。）的基因转移系统的过程中。菌株BH68K，已经确定了两个主要的限制性障碍。细胞壁相关的核酸酶表现出共价闭合的环状和线性双链DNA分子（包括Cyanothece sp。）的非位点特异性降解。菌株BH68K染色体DNA。通过使用水或含Triton X-100的缓冲液，核酸酶很容易从完整细胞中释放出来。从水洗细胞制备的细胞提取物中无法检测到核酸酶活性。 Cyanothece sp。的限制性核酸内切酶敏感性的比较。菌株BH68K DNA到鱼腥藻的DNA。 PCC 7120菌株显示这些生物具有几乎相同的限制模式，因此可能包含类似的DNA甲基化系统。 DpnI，MboI和Sau3AI的限制表明存在腺嘌呤甲基化。蓝藻菌株BH68K细胞提取物含有II型限制性核酸内切酶Csp68KI。无需大量纯化即可轻松在细胞提取物中检测Csp68KI的活性。 Csp68KI是AvaII的同分异构体，可识别5'-GG（A / T）CC-3'核苷酸序列。在产生3-bp 5'突出端的鸟苷核苷酸之间发生切割。

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