背景:原核Argonaute(pAgo)蛋白是众所周知的寡核苷酸指导的内切核酸酶,其含有核酸内切酶活性所需的保守PIWI结构域。与pAgos有远缘关系,PIWI-RE家族,定义为具有保守R和E残基的PIWI,有人建议表现出不同的活动。需要阐明PIWI-RE家族成员独特的生化特性和生理功能,以探索其在基因编辑中的应用。
结果:这里,我们描述了来自Stutzeri假单胞菌(PsPIWI-RE)的PIWI-RE家族蛋白的催化性能和细胞功能。结构模型表明,该蛋白质具有类似于pAgo的PIWI结构,但具有不同的PAZ样和N端结构域。与以前报道的pAgos不同,重组PsPIWI-RE充当RNA指导的DNA核酸酶,以及DNA指导的RNA核酸酶。它在20至65°C的温度范围内切割单链DNA,最佳温度为45℃。在D525或D610突变显著降低其核酸内切酶活性,确认这两个残基都是催化的关键。与野生型相比,PIWI-RE敲除突变体对环丙沙星作为DNA复制抑制剂更敏感,提示PIWI-RE可能参与DNA复制。
结论:我们的研究为未知的PIWI-RE蛋白质家族的可编程核酸酶活性和生物学功能提供了第一个见解,强调它们在体内的重要作用以及在基因组DNA修饰中的潜在应用。
BACKGROUND: Prokaryotic Argonaute (pAgo) proteins are well-known oligonucleotide-directed endonucleases, which contain a conserved PIWI domain required for
endonuclease activity. Distantly related to pAgos, PIWI-RE family, which is defined as PIWI with conserved R and E residues, has been suggested to exhibit divergent activities. The distinctive biochemical properties and physiological functions of PIWI-RE family members need to be elucidated to explore their applications in gene editing.
RESULTS: Here, we describe the catalytic performance and cellular functions of a PIWI-RE family protein from Pseudomonas stutzeri (PsPIWI-RE). Structural modelling suggests that the protein possesses a PIWI structure similar to that of pAgo, but with different PAZ-like and N-terminal domains. Unlike previously reported pAgos, recombinant PsPIWI-RE acts as an RNA-guided DNA nuclease, as well as a DNA-guided RNA nuclease. It cleaves single-stranded DNA at temperatures ranging from 20 to 65 °C, with an optimum temperature of 45 °C. Mutation at D525 or D610 significantly reduced its
endonuclease activity, confirming that both residues are key for catalysis. Comparing with wild-type, mutant with PIWI-RE knockout is more sensitive to ciprofloxacin as DNA replication inhibitor, suggesting PIWI-RE may potentially be involved in DNA replication.
CONCLUSIONS: Our study provides the first insights into the programmable nuclease activity and biological function of the unknown PIWI-RE family of proteins, emphasizing their important role in vivo and potential application in genomic DNA modification.