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==Phosphopantetheine adenylyltransferase (PPAT) from psychrophilic methanotroph Methylocapsa palsarum==
<StructureSection load='9xwd' size='340' side='right'caption='[[9xwd]], [[Resolution|resolution]] 2.20&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[9xwd]] is a 6 chain structure with sequence from [https://en.wikipedia.org/wiki/Methylocapsa_palsarum Methylocapsa palsarum]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=9XWD OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=9XWD 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]] 2.2&#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=9xwd FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=9xwd OCA], [https://pdbe.org/9xwd PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=9xwd RCSB], [https://www.ebi.ac.uk/pdbsum/9xwd PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=9xwd ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/A0A1I4C747_9HYPH A0A1I4C747_9HYPH] Reversibly transfers an adenylyl group from ATP to 4'-phosphopantetheine, yielding dephospho-CoA (dPCoA) and pyrophosphate.[HAMAP-Rule:MF_00151]
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== Publication Abstract from PubMed ==
Phosphopantetheine adenylyltransferase (PPAT), a key enzyme in the universal Coenzyme A biosynthetic pathway, is essential for cellular metabolism. However, the adaptive mechanisms of PPAT in psychrophilic (cold-adapted) organisms remain poorly understood. Here, we characterize PPAT from the psychrophilic methanotroph Methylocapsa palsarum (MpaPPAT). Sequence analysis identified a unique five-amino-acid insertion (SCRLS) within a surface-exposed loop, a feature conserved among psychrophilic homologues. To investigate its function, we determined the crystal structures of wild-type (WT) MpaPPAT and a loop-deletion mutant (MpaPPAT(Delta67-71)) and performed comparative biochemical analyses. Structurally, MpaPPAT forms a dimer-of-trimers hexamer. Biochemically, WT MpaPPAT maintains high catalytic activity at low temperatures (10-20 degrees C), whereas the MpaPPAT(Delta67-71) mutant exhibits impaired cold activity. The mutant structure reveals that the deletion of the distant surface loop induces a long-range allosteric change, resulting in a dual impairment: 1) a stabilization and rigidification ("clamping") of the central alpha-helix 4 (H4) at the hexameric core interface, and 2) a dramatic shift in the central pore's electrostatic potential from positive (WT) to negative (mutant). Our findings reveal that the SCRLS insertion is a critical allosteric modulator that provides a sophisticated dual mechanism for enzymatic cold adaptation. It maintains the conformational flexibility of the hexameric core, preventing the "clamping" effect, and simultaneously ensures a positively charged central channel to electrostatically steer negatively charged substrates (ATP and phosphopantetheine) into the active site, thereby overcoming the kinetic challenges of a low-temperature environment.

A remote surface loop modulates core structure and cold activity in phosphopantetheine adenylyltransferase.,Nam Y, Hwang J, Kim B, Lee JH, Do H PLoS One. 2026 Mar 12;21(3):e0342296. doi: 10.1371/journal.pone.0342296. , eCollection 2026. PMID:41818184<ref>PMID:41818184</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Methylocapsa palsarum]]
[[Category: Do H]]
[[Category: Hwang J]]
[[Category: Nam Y]]