Pseudomonas aeruginosa phage PaP1 DNA polymerase is an A-family DNA polymerase demonstrating ssDNA and dsDNA 3′–5′ exonuclease activity

• Published in: Virus genes Vol. 52; no. 4; pp. 538 - 551
• Main Authors: Liu, Binyan, Gu, Shiling, Liang, Nengsong, Xiong, Mei, Xue, Qizhen, Lu, Shuguang, Hu, Fuquan, Zhang, Huidong
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.08.2016; Springer Nature B.V
• Subjects: Amino Acid Sequence; Bacteriophages - genetics; Biomedical and Life Sciences; Biomedicine; DNA - genetics; DNA Replication - genetics; DNA, Single-Stranded - genetics; DNA-Directed DNA Polymerase - genetics; Exonucleases - genetics; Medical Microbiology; Pancreatitis-Associated Proteins; Plant Sciences; Pseudomonas aeruginosa; Pseudomonas aeruginosa - genetics; Sequence Alignment; Thioredoxins - genetics; Virology; DNA polymerase; Phage PaP1; Exonuclease; Pseudomonas aeruginosa
• ISSN: 0920-8569; 1572-994X
• DOI: 10.1007/s11262-016-1329-7

Most phages contain DNA polymerases, which are essential for DNA replication and propagation in infected host bacteria. However, our knowledge on phage-encoded DNA polymerases remains limited. This study investigated the function of a novel DNA polymerase of PaP1, which is the lytic phage of Pseudomonas aeruginosa . PaP1 encodes its sole DNA polymerase called Gp90 that was predicted as an A-family DNA polymerase with polymerase and 3′–5′ exonuclease activities. The sequence of Gp90 is homologous but not identical to that of other A-family DNA polymerases, such as T7 DNA polymerases (Pol) and DNA Pol I. The purified Gp90 demonstrated a polymerase activity. The processivity of Gp90 in DNA replication and its efficiency in single-dNTP incorporation are similar to those of T7 Pol with processive thioredoxin (T7 Pol/trx). Gp90 can degrade ssDNA and dsDNA in 3′–5′ direction at a similar rate, which is considerably lower than that of T7 Pol/trx. The optimized conditions for polymerization were a temperature of 37 °C and a buffer consisting of 40 mM Tris–HCl (pH 8.0), 30 mM MgCl 2 , and 200 mM NaCl. These studies on DNA polymerase encoded by PaP1 help advance our knowledge on phage-encoded DNA polymerases and elucidate PaP1 propagation in infected P. aeruginosa .