Biology subjects

Latham, M.

Publications and source records attributed to Latham, M..

3 recordsLinked to original sources

bioRxiv2026

How a highly acidic SH3 domain binds to its intrinsically disordered partner through the formation of an encounter complex intermediate

Electrostatic interactions often play a role in determining the thermodynamic and kinetic properties of protein-protein interactions. However, the role of long-range electrostatic interactions in intrinsically disordered protein (IDP) binding is less clear, as they often bind in multiple steps including initial formation of a disordered encounter complex, followed by rearrangement into the bound state. We varied the salt concentration to probe the role of long-range electrostatic interactions in the binding of the highly charged AbpSH3 domain and the oppositely charged IDP ArkA. Using isothermal titration calorimetry, we observe that salt enthalpically destabilizes the bound complex. Molecular dynamics and NMR experiments reveal that salt has little effect on the bound state structure. However, simulations show that salt destabilizes the encounter complex intermediate, which primarily affects the association rate as measured by NMR. Consistent with these results, salt has the largest stabilizing effect on the apo SH3 domain, as cations substitute for the transient and long-range electrostatic interactions that can form with ArkA in the complex. We reveal a detailed picture of how a highly charged domain uses long-range, fuzzy, electrostatic interactions to help reach the bound state, a mechanism that is likely common among other highly charged domains that bind IDPs. TOC Image O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=96 SRC="FIGDIR/small/741257v1_ufig1.gif" ALT="Figure 1000"> View larger version (21K): org.highwire.dtl.DTLVardef@dfc7acorg.highwire.dtl.DTLVardef@1ae0438org.highwire.dtl.DTLVardef@19704adorg.highwire.dtl.DTLVardef@1b40b15_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

bioRxiv2025

Alternatively-Spliced CAMKK2 isoforms drive differential metabolic stress response and the regulation of ferroptosis

Calcium/Calmodulin-dependent protein kinase kinase 2 (CAMKK2) is a multifunctional kinase that regulates metabolic processes by phosphorylating downstream targets. CAMKK2 is expressed as several highly similar protein isoforms, although the specific functions of these individual isoforms remain largely unexplored. These isoforms have been shown to display tissue-specific expression patterns, suggesting unique roles in distinct cellular contexts. In this study, we investigated the biochemical and functional relevance of CAMKK2 isoforms, LF and SF, in the context of glucose metabolism. Co-immunoprecipitation experiments revealed that the LF isoform preferentially binds the adaptor protein 14-3-3, while the SF isoform interacts with Calmodulin. Furthermore, the interaction between SF and Calmodulin was enhanced upon glucose starvation, whereas this interaction was not observed for LF. To assess their functional significance, we generated doxycycline-inducible, isoform-specific HeLa cell lines. Under low glucose conditions, cells expressing the LF isoform failed to activate AMPK, while cells expressing the SF isoform exhibited robust increase in AMPK phosphorylation. Moreover, LF-expressing cells accumulated higher levels of reactive oxygen species, upregulated ferroptosis-related genes via BACH1/NRF2, and displayed increased cell death compared to SF-expressing cells. Collectively, these findings demonstrate that CAMKK2 isoforms exhibit differential selectivity for protein partners and mediate distinct downstream signaling pathways, impacting metabolism in cancer.

biochemistry↗

bioRxiv2021

LRET-derived HADDOCK structural models describe the conformational heterogeneity required for processivity of the Mre11-Rad50 DNA damage repair complex

The Mre11-Rad50-Nbs1 protein complex is one of the first responders to DNA double strand breaks. Studies have shown that the catalytic activities of the evolutionarily conserved Mre11-Rad50 (MR) core complex depend on an ATP-dependent global conformational change that takes the macromolecule from an open, extended structure in the absence of ATP to a closed, globular structure when ATP is bound. We have previously identified an additional partially open conformation using Luminescence Resonance Energy Transfer (LRET) experiments. Here, a combination of LRET and the molecular docking program HADDOCK was used to further investigate this partially open state and identify three conformations of ATP-bound MR in solution: closed, partially open, and open, which are in addition to the extended, apo conformation. These models are supported with mutagenesis and SAXS data that corroborate the presence of these three states and suggest a mechanism for the processivity of the MR complex along the DNA.

biophysics↗