3KET CRYSTAL STRUCTURE OF A REX-FAMILY TRANSCRIPTIONAL REGULATORY PROTEIN FROM STREPTOCOCCUS AGALACTIAE BOUND TO A PALINDROMIC OPERATOR TRANSCRIPTION/DNA, PROTEIN-DNA COMPLEX, WINGED HELIX, ROSSMANN FOLD, NAD+, REPRESSOR, TRANSCRIPTION, TRANSCRIPTION REGULATION, REDOX SENSING, TRANSCRIPTION-DNA COMPLEX