View source for 22aq


==The costructure of MitM and dehydromitomycin B with SAH==
<StructureSection load='22aq' size='340' side='right'caption='[[22aq]], [[Resolution|resolution]] 3.02&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[22aq]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Streptomyces_caespitosus Streptomyces caespitosus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=22AQ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=22AQ FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 3.02&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=SAH:S-ADENOSYL-L-HOMOCYSTEINE'>SAH</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=22aq FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=22aq OCA], [https://pdbe.org/22aq PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=22aq RCSB], [https://www.ebi.ac.uk/pdbsum/22aq PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=22aq ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/Q9X5Q9_STRLA Q9X5Q9_STRLA] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
S-Adenosyl-l-methionine (SAM)-dependent methyltransferases (MTs) play important roles in many biological processes by catalyzing a methylation reaction. Proteins with a similar MT-fold to enable catalytic abilities rather than methylation were evidenced, but revealing these abilities appears to be a challenge to bioinformatics analysis unless experimental efforts are involved. Based on comprehensive investigations into MitM in the biosynthesis of mitomycins, the clinically important antitumor antibiotics, we report here that this MT catalyzes reactions more than methylation. MitM primarily acts as a C9a-O-MT for methylating the 6/5/5/3-fused aziridinomitosane (AMS) skeleton that is shared by many known mitomycin variables in C9 stereoselectivity and aziridine-N-methylation. Further, this MT can process AMS for C9a-O-methoxy elimination, aziridine hydrolysis/opening, and subsequent C1-O- and C2-N-methylations. Gene inactivation, biochemical characterization, substrate/product cocrystallization, and site-specific mutagenesis rationalized the mechanisms by which the MT-fold of MitM is repurposed to deliver such an extraordinary capability, facilitating the observation of a few new antitumor mitomycins that were not recognized previously in the producing strain. This study attracts attention to uncharacterized MT-fold proteins, which have millions of sequences in databases but remain to be appreciated in catalytic function.

A Methyltransferase Catalyzing Reactions More Than Methylation.,Wang S, Huang J, Xia M, Bi S, Wang J, Fang P, Liu W J Am Chem Soc. 2026 May 13;148(18):19061-19073. doi: 10.1021/jacs.6c02250. Epub , 2026 Apr 29. PMID:42057505<ref>PMID:42057505</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 22aq" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Streptomyces caespitosus]]
[[Category: Fang P]]
[[Category: Liu W]]
[[Category: Wang S]]
[[Category: Xia M]]