Hrq1 facilitates nucleotide excision repair of DNA damage induced by 4-nitroquinoline-1-oxide and cisplatin in Saccharomyces cerevisiae

Abstract

Hrq1 helicase is a novel member of the RecQ family. Among the five human RecQ helicases, Hrq1 is most homologous to RECQL4 and is conserved in fungal genomes. Recent genetic and biochemical studies have shown that it is a functional gene, involved in the maintenance of genome stability. To better define the roles of Hrq1 in yeast cells, we investigated genetic interactions between HRQ1 and several DNA repair genes. Based on DNA damage sensitivities induced by 4-nitroquinoline-1-oxide (4-NQO) or cisplatin, RAD4 was found to be epistatic to HRQ1. On the other hand, mutant strains defective in either homologous recombination (HR) or post-replication repair (PRR) became more sensitive by additional deletion of HRQ1, indicating that HRQ1 functions in the RAD4-dependent nucleotide excision repair (NER) pathway independent of HR or PRR. In support of this, yeast two-hybrid analysis showed that Hrq1 interacted with Rad4, which was enhanced by DNA damage. Overexpression of Hrq1K318A helicase-deficient protein rendered mutant cells more sensitive to 4-NQO and cisplatin, suggesting that helicase activity is required for the proper function of Hrq1 in NER.

The RecQ‐like helicase HRQ1 is involved in DNA crosslink repair in Arabidopsis in a common pathway with the Fanconi anemia‐associated nuclease FAN1 and the postreplicative repair ATPase RAD5A

“…For the Arabidopsis homolog AtRAD1, an involvement in NER could be confirmed (Fidantsef et al ., ). As yeast Hrq1 was demonstrated to act in NER, the determination of interactions in Arabidopsis were of special interest (Groocock et al ., ; Choi et al ., ). Therefore, we generated the hrq1‐1rad1‐1 double mutant and analyzed its sensitivity to the CL agents cisplatin and MMC in comparison to both single mutants and the WT (Fig.…”

“…In conformity with other RecQ helicases, an ATP‐dependent 3′‐5′ helicase activity was shown for Hrq1 (Groocock et al ., ; Kwon et al ., ). Epistasis analyses revealed a role for Hrq1 in the repair of cisplatin‐induced intrastrand crosslinks (CLs) via nucleotide excision repair (NER), in parallel to postreplicative repair (PRR) and homologous recombination (HR) (Groocock et al ., ; Choi et al ., ). Epistasis analyses with the other RecQ helicase in baker's yeast, Sgs1, revealed that Hrq1 is the main helicase in response to mitomycin C (MMC)‐induced interstrand CLs, while Sgs1 possesses only a backup function (Bochman et al ., ).…”

Characterization of Hrq1-Rad14 Interaction in Saccharomyces cerevisiae

“…양성 대조군으로는 pGAD-RNR2 와 pGBD-RNR4를 사용하였다 (Choi et al, 2014). RNA2와 RNR4는 효모의 ribonucleotide reductase를 암호화하는 유전자 로서 복합체를 형성하여 효소활성에 필수적인 작은 소단위를 구성 한다 (Huang and Elledge, 1997;Wang et al, 1997)…”

“…Hrq1과 Rad14 사이의 two-hybrid 상호작용은 4-NQO 처리에 의해 증가하였으며, 이러한 상호작용의 증가는 Rad4에 의존적인 것으로 보아 NER의 활성화와 관련이 있을 것 으로 생각된다. 최근 본 연구진은 상위 분석을 통해서 RAD4 유 전자가 HRQ1의 상위에서 작용한다는 것을 보고하였다 (Choi et al, 2014). 이 연구에서 여러 가지 DNA 수선 돌연변이들과 hrq1Δ 이중돌연변이는 단일 돌연변이들보다 4-NQO에 대한 민 감성이 증가한 반면, rad4Δ 돌연변이에 대해서는 hrq1Δ 돌연변 이가 아무런 영향을 주지 않았다.…”

“…4의 결과와 일치하는 것이다. 뿐만 아니라 Hrq1과 Rad4 사 이에도 two-hybrid 상호작용이 관찰되었다 (Choi et al, 2014). 그러나 Hrq1과 Rad14 사이의 two-hybrid 상호작용은 rad4Δ 돌 연변이 background에서도 관찰되기 때문에 (Fig.…”