Resolving fast and slow motions in the internal loop containing stem-loop 1 of HIV-1 that are modulated by Mg2+ binding: role in the kissing-duplex structural transition.

ABSTRACT: Stem loop 1 (SL1) is a highly conserved hairpin in the 5'-leader of the human immunodeficiency virus type I that forms a metastable kissing dimer that is converted during viral maturation into a stable duplex with the aid of the nucleocapsid (NC) protein. SL1 contains a highly conserved internal loop that promotes the kissing-duplex transition by a mechanism that remains poorly understood. Using NMR, we characterized internal motions induced by the internal loop in an SL1 monomer that may promote the kissing-duplex transition. This includes micro-to-millisecond secondary structural transitions that cause partial melting of three base-pairs above the internal loop making them key nucleation sites for exchanging strands and nanosecond rigid-body stem motions that can help bring strands into

SUBMITTER: Sun X 

PROVIDER: S-EPMC1865058 | biostudies-literature | 2007

REPOSITORIES: biostudies-literature