title: Pisum sativum p68 DEAD-box protein is ATP-dependent RNA helicase and unique bipolar DNA helicase.
abstract: DEAD-box helicases play essential role in DNA and RNA metabolism such as replication, repair, recombination, transcription, translation, ribosome biogenesis and splicing which regulate plant growth and development. The presence of helicases in the stress-induced ORFs identified by cDNA microarray indicates that helicases might be playing an important role in stabilizing growth in plants under stress. p68 DEAD-box helicase has been identified and characterized from animal systems but the properties and functions of plant p68 are poorly understood. In this study, the identification, purification and characterization of recombinant p68 from Pisum sativum (Psp68) is presented. Psp68 possesses all the characteristic motifs like DEAD-box ATP-binding and helicase C terminal motifs and is structurally similar to human p68 homologue. Psp68 exhibits ATPase activity in the presence of both DNA and RNA and it binds to DNA as well as RNA. It contains the characteristic RNA helicase activity. Interestingly Psp68 also shows the unique DNA helicase activity, which is bipolar in nature (unwinds DNA in both the 5'-3' and 3'-5' directions). The Km values of Psp68 for ATPase are 0.5126 and 0.9142 mM in the presence of DNA and RNA, respectively. The Km values of Psp68 are 1.6129 and 1.14 nM for DNA helicase and RNA helicase, respectively. The unique properties of Psp68 suggest that it could be a multifunctional protein involved in different aspect of DNA and RNA metabolism. This discovery should make an important contribution to better understanding of nucleic acids metabolism plants.
authors.affiliation: International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India, narendra@icgeb.res.in.
authors.forename: Narendra
authors.initials: N
authors.lastname: Tuteja
authors.forename: Mohammed
authors.initials: M
authors.lastname: Tarique
authors.forename: Mst Sufara Akhter
authors.initials: MS
authors.lastname: Banu
authors.forename: Moaz
authors.initials: M
authors.lastname: Ahmad
authors.forename: Renu
authors.initials: R
authors.lastname: Tuteja
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D053487:DEAD-box RNA Helicases / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D004265:DNA Helicases / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018532:Pisum sativum / Q000201:enzymology*; D010940:Plant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D010940:Plant Proteins; D011994:Recombinant Proteins; D004265:DNA Helicases; D053487:DEAD-box RNA Helicases