UMSBP from Leishmania donovani UR6 recognizes single-stranded nucleotides at the site of origin of replication of kinetoplast minicircles

摘要

Kinetoplastidae is a family of parasitic protozoa having a single mitochondrion per cell which is termed kinetoplast, containing a unique network of DNA of two kinds, namely minicircles and maxicircles. Replication of these DNAs, particularly minicircles which are in 10,000 copies, is of great interest. A protein that binds to a single-stranded universal minicircule sequence DNA (UMSDNA) of Leishmania donovani has been isolated to its apparent homogeneity. This protein recognizes a conserved dodecamer with the sequence 5'-GGGGTTGGTGTA-3' at: the heavy strand of minicircle DNA. The protein is a dimer of calculated relative molecular mass (Mr) of 82 kDa. The protein also recognizes other single-stranded oligomers such as UMs-like sequences and an oligomer having single UMS site. However, it never binds to duplex DNAs and perhaps electrostatic interaction and monovalent cations play a pivotal role in UMS-UMSBP (Universal minicircle sequence binding protein) complex formation. [References: 33]