Structures of MfnG, an O-methyltranseferase involved in the biosynthese of marformycins, from multiple crystal forms

Presented During:

07/31/2022: 5:30 PM - 7:30 PM
Portland Marriott Downtown Waterfront  


2022: 72nd ACA Annual Meeting

Session Type:


Presenting Author :

Mitchell D. Miller  
Rice University

Additional Author(s):

Kuan-Lin Wu  
Rice University
Weijun Xu  
Rice University
Han Xiao  
Rice University
George N. Phillips, Jr.  
Rice University

Abstract Body:

Marformycins are anti-infective natural products isolated from a deep sea sediment-derived Streptomyces drozdowiczii strain. These cyclodepsipetides contain O-methyl-D-Tyr. Liu et al., (Org. Lett. 2015, 17, 1509–1512) identified a SAM-dependent O-methyltransferase, MfnG, in the marformycins biosynthetic gene cluster and found it capable of methylating the phenoic oxygen of both D-Tyr and L-Tyr in vitro.

To better understand this enzyme's structural recognition and function, we have determined the MfnG structure using X-ray crystallography. Despite adding S-adenosyl-L-methionine (SAM/AdoMet) to the protein during crystallization, we found the spent product, S-Adenosyl-L-homocysteine (SAH/AdoHcy), bound. Since the SAH is unreactive, we were able to soak in L-Tyrosine to obtain a structure with the methyl doner product (SAH) and a methyl acceptor substrate (L-Tyr).

We found MfnG could crystalize from a number of different screening conditions and that these crystals had different unit cell parameters. To date, we have phased 5 forms (2 forms in P212121, 2 forms in P21 and a P1 form), which contain one to four dimers (2-8 protomers) per asymmetric unit. Here we compare the packing arrangement in these different crystal packing forms.

This work was supported in part by the NSF (STC 1231306), NIH/NIGMS (R01-GM115261, R35-GM133706), NIH/NIAID (R01-AI165079), NIH/NCI (R01-CA217255, R21-CA255894), US DOD (W81XWH-21-1-0789), Texas CPRIT (RR170014) and the Robert A. Welch Foundation (C-1970). The content is solely the responsibility of the authors and does not necessarily represent the official views of the Funders.

Additional Information - Poster (2022)

Are you registered for the ACA meeting?


For scheduling purposes please select a session that most matches your poster topic. If your poster theme does not align with the topics of the sessions, please select a general category.


If submitted for a poster would you like to be considered for a poster prize?