PT  - JOURNAL ARTICLE
AU  - Tamar (Skaist) Mehlman
AU  - Justin T. Biel
AU  - Syeda Maryam Azeem
AU  - Elliot R. Nelson
AU  - Sakib Hossain
AU  - Louise E. Dunnett
AU  - Neil G. Paterson
AU  - Alice Douangamath
AU  - Romain Talon
AU  - Danny Axford
AU  - Helen Orins
AU  - Frank von Delft
AU  - Daniel A. Keedy
TI  - Room-temperature crystallography reveals altered binding of small-molecule fragments to PTP1B
AID  - 10.1101/2022.11.02.514751
DP  - 2022 Jan 01
TA  - bioRxiv
PG  - 2022.11.02.514751
4099  - http://biorxiv.org/content/early/2022/11/03/2022.11.02.514751.short
4100  - http://biorxiv.org/content/early/2022/11/03/2022.11.02.514751.full
AB  - Much of our current understanding of how small-molecule ligands interact with proteins stems from X-ray crystal structures determined at cryogenic (cryo) temperature. For proteins alone, room-temperature (RT) crystallography can reveal previously hidden, biologically relevant alternate conformations. However, less is understood about how RT crystallography may impact the conformational landscapes of protein-ligand complexes. Previously we showed that small-molecule fragments cluster in putative allosteric sites using a cryo crystallographic screen of the therapeutic target PTP1B (Keedy*, Hill*, 2018). Here we have performed two RT crystallographic screens of PTP1B using many of the same fragments, representing the largest RT crystallographic screens of a diverse library of ligands to date, and enabling a direct interrogation of the effect of data collection temperature on protein-ligand interactions. We show that at RT, fewer ligands bind, and often more weakly -- but with a variety of temperature-dependent differences, including unique binding poses, changes in solvation, new binding sites, and distinct protein allosteric conformational responses. Overall, this work suggests that the vast body of existing cryogenic-temperature protein-ligand structures may provide an incomplete picture, and highlights the potential of RT crystallography to help complete this picture by revealing distinct conformational modes of protein-ligand systems. Our results may inspire future use of RT crystallography to interrogate the roles of protein-ligand conformational ensembles in biological function.Competing Interest StatementThe authors have declared no competing interest.