X-ray free-electron laser studies reveal correlated motion during isopenicillin N synthase catalysis.
Rabe P., Kamps JJAG., Sutherlin KD., Linyard JDS., Aller P., Pham CC., Makita H., Clifton I., McDonough MA., Leissing TM., Shutin D., Lang PA., Butryn A., Brem J., Gul S., Fuller FD., Kim I-S., Cheah MH., Fransson T., Bhowmick A., Young ID., O'Riordan L., Brewster AS., Pettinati I., Doyle M., Joti Y., Owada S., Tono K., Batyuk A., Hunter MS., Alonso-Mori R., Bergmann U., Owen RL., Sauter NK., Claridge TDW., Robinson CV., Yachandra VK., Yano J., Kern JF., Orville AM., Schofield CJ.
Isopenicillin N synthase (IPNS) catalyzes the unique reaction of l-δ-(α-aminoadipoyl)-l-cysteinyl-d-valine (ACV) with dioxygen giving isopenicillin N (IPN), the precursor of all natural penicillins and cephalosporins. X-ray free-electron laser studies including time-resolved crystallography and emission spectroscopy reveal how reaction of IPNS:Fe(II):ACV with dioxygen to yield an Fe(III) superoxide causes differences in active site volume and unexpected conformational changes that propagate to structurally remote regions. Combined with solution studies, the results reveal the importance of protein dynamics in regulating intermediate conformations during conversion of ACV to IPN. The results have implications for catalysis by multiple IPNS-related oxygenases, including those involved in the human hypoxic response, and highlight the power of serial femtosecond crystallography to provide insight into long-range enzyme dynamics during reactions presently impossible for nonprotein catalysts.