A TRANSITION FROM STRONG RIGHT-HANDED TO CANONICAL LEFT-HANDED SUPERCOILING IN A CONSERVED COILED COIL SEGMENT OF TRIMERIC AUTOTRANSPORTER ADHESINS - THE M1 MUTANT STRUCTURE 3H7Z CELL ADHESION, YADA, ADHESION, ADHESIN, COILED COIL, MUTANT, CELL MEMBRANE, CELL OUTER MEMBRANE, MEMBRANE, PLASMID, VIRULENCE