M regulator protein trans-acting positive regulator (Mga) is a DNA-binding protein that activates the expression of several important virulence genes in group A streptococcus in response to changing environmental conditions. This domain is found in the centre of the Mga proteins. This family also contains a number of bacterial RofA transcriptional regulators that seem to be largely restricted to streptococci. These proteins have been shown to regulate the expression of important bacterial adhesins. This is presumably a DNA-binding domain.