View source for 23lq


==Crystal structure of AprI==
<StructureSection load='23lq' size='340' side='right'caption='[[23lq]], [[Resolution|resolution]] 2.51&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[23lq]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Streptoalloteichus_tenebrarius Streptoalloteichus tenebrarius]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=23LQ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=23LQ 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]] 2.51&#8491;</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=23lq FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=23lq OCA], [https://pdbe.org/23lq PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=23lq RCSB], [https://www.ebi.ac.uk/pdbsum/23lq PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=23lq ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/Q2MFJ8_STRSD Q2MFJ8_STRSD] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Apramycin biosynthesis features an unusual O-5 phosphorylation on octose-containing pseudotrisaccharide intermediates that functions as a pathway recognition tag. AprI catalyzes 7'-N-methylation of the phosphorylated intermediate. Unexpectedly, sequence and phylogenetic analysis place AprI within the HemK/PrmC superfamily of protein-targeting methyltransferases rather than among canonical small-molecule N-methyltransferases. Here, we report the crystal structures of AprI in apo and SAH-bound forms, revealing a clasp-like homodimer formed by the N-terminal region and a highly dynamic substrate-proximal loop. Structure-guided docking, molecular dynamics simulations, and mutational analysis show that the homodimer forms a composite, positively charged pocket for recognition of the O-5 phosphate tag, whereas the flexible loop positions the 7'-amino group of the pseudotrisaccharide substrate for methyl transfer. Together, these findings establish AprI as an unusual PrmC-like protein methyltransferase repurposed for tailoring phosphorylated natural products, and open opportunities to engineer biocatalysts for site-selective aminoglycoside diversification.

Phosphate-tagged substrate recognition by a PrmC-like methyltransferase in apramycin biosynthesis.,Zhang Q, Zhang Y, Cui Y, Deng Z, Zhao Q, Long F, Yu Y Int J Biol Macromol. 2026 Aug;372:153063. doi: 10.1016/j.ijbiomac.2026.153063. , Epub 2026 Jun 16. PMID:42297172<ref>PMID:42297172</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 23lq" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Streptoalloteichus tenebrarius]]
[[Category: Yu Y]]
[[Category: Zhang Q]]
[[Category: Zhang YX]]