sentences:  The related protein, gamma-delta resolvase shares high similarity to Hin, of which much structural work has been done, including structures bound to DNA and reaction intermediates.Hin functions to invert a 900 base pair (bp) DNA segment within the salmonella genome that contains a promoter for downstream flagellar genes, fljA and fljB.Inversion of the intervening DNA alternates the direction of the promoter and thereby alternates expression of the flagellar genes.