Simian AIDS type D serogroup 2 retrovirus: isolation of an infectious molecular clone and sequence analyses of its envelope glycoprotein gene and 3' long terminal repeat.

We describe the molecular cloning of a serogroup 2 simian retrovirus (SRV; D2/RHE/OR) and present the sequence of its envelope (env) glycoprotein gene and 3' long terminal repeat region. This report documents the first infectious molecular clone of a serogroup 2 SRV and provides env sequence verification of genetic diversity among serogroup 2 SRV isolates.

The Arc and Mnt repressors. A new class of sequence-specific DNA-binding protein.

Genetic, biochemical, and biophysical studies have begun to reveal details of the structures of Arc and Mnt and show that these repressors use residues at their N-terminal ends for operator recognition and binding. Some of the DNA contacts made by these residues have been identified, and this information together with NMR studies has permitted the construction of models of the DNA binding region. Although the accuracy of these models remains to be determined, it seems clear that Arc and Mnt are members of a new class of DNA-binding proteins.

Sequence-specific binding of arc repressor to DNA. Effects of operator mutations and modifications.

A set of arc operators with transition and/or transversion mutations at each operator base pair has been constructed. By determining the ability of Arc to bind these variant operators, the importance of each base pair for Arc recognition has been assessed. Methylation protection experiments have also been used to probe points of close contact between Arc and most of the mutant operators. These data, together with phosphate interference results obtained previously for the wild type operator, provide information about the operator surface that is contacted when Arc binds.