Publications by authors named "W A Hendrickson"

301 Publications

Conformational equilibria in allosteric control of Hsp70 chaperones.

Mol Cell 2021 Aug 26. Epub 2021 Aug 26.

Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA. Electronic address:

Heat-shock proteins of 70 kDa (Hsp70s) are vital for all life and are notably important in protein folding. Hsp70s use ATP binding and hydrolysis at a nucleotide-binding domain (NBD) to control the binding and release of client polypeptides at a substrate-binding domain (SBD); however, the mechanistic basis for this allostery has been elusive. Here, we first characterize biochemical properties of selected domain-interface mutants in bacterial Hsp70 DnaK. We then develop a theoretical model for allosteric equilibria among Hsp70 conformational states to explain the observations: a restraining state, Hsp70-ATP, restricts ATP hydrolysis and binds peptides poorly, whereas a stimulating state, Hsp70-ATP, hydrolyzes ATP rapidly and has high intrinsic substrate affinity but rapid binding kinetics. We support this model for allosteric regulation with DnaK structures obtained in the postulated stimulating state S with biochemical tests of the S-state interface and with improved peptide-binding-site definition in an R-state structure.
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http://dx.doi.org/10.1016/j.molcel.2021.07.039DOI Listing
August 2021

Cost-effectiveness of behavioral and pelvic floor muscle therapy combined with midurethral sling surgery vs surgery alone among women with mixed urinary incontinence: results of the Effects of Surgical Treatment Enhanced With Exercise for Mixed Urinary Incontinence randomized trial.

Am J Obstet Gynecol 2021 Jul 6. Epub 2021 Jul 6.

Social, Statistical, and Environmental Sciences, RTI International, Research Triangle Park, NC.

Background: Urinary incontinence is prevalent among women, and it has a substantial economic impact. Mixed urinary incontinence, with both stress and urgency urinary incontinence symptoms, has a greater adverse impact on quality of life and is more complex to treat than either stress or urgency urinary incontinence alone. Studies evaluating the cost-effectiveness of treating both the stress and urgency urinary incontinence components simultaneously are lacking.

Objective: Cost-effectiveness was assessed between perioperative behavioral and pelvic floor muscle therapies combined with midurethral sling surgery and midurethral sling surgery alone for the treatment of women with mixed urinary incontinence. The impact of baseline severe urgency urinary incontinence symptoms on cost-effectiveness was assessed.

Study Design: This prospective economic evaluation was performed concurrently with the Effects of Surgical Treatment Enhanced with Exercise for Mixed Urinary Incontinence randomized trial that was conducted from October 2013 to April 2016. Participants included 480 women with moderate-to-severe stress and urgency urinary incontinence symptoms and at least 1 stress urinary incontinence episode and 1 urgency urinary incontinence episode on a 3-day bladder diary. The primary within-trial analysis was from the healthcare sector and societal perspectives, with a 1-year time horizon. Costs were in 2019 US dollars. Effectiveness was measured in quality-adjusted life-years and reductions in urinary incontinence episodes per day. Incremental cost-effectiveness ratios of combined treatment vs midurethral sling surgery alone were calculated, and cost-effectiveness acceptability curves were generated. Analysis was performed for the overall study population and subgroup of women with Urogenital Distress Inventory irritative scores of ≥50th percentile.

Results: The costs for combined treatment were higher than the cost for midurethral sling surgery alone from both the healthcare sector perspective ($5100 [95% confidence interval, $5000-$5190] vs $4470 [95% confidence interval, $4330-$4620]; P<.01) and the societal perspective ($9260 [95% confidence interval, $8590-$9940] vs $8090 [95% confidence interval, $7630-$8560]; P<.01). There was no difference between combined treatment and midurethral sling surgery alone in quality-adjusted life-years (0.87 [95% confidence interval, 0.86-0.89] vs 0.87 [95% confidence interval, 0.86-0.89]; P=.90) or mean reduction in urinary incontinence episodes per day (-4.76 [95% confidence interval, -4.51 to 5.00] vs -4.50 [95% confidence interval, -4.25 to 4.75]; P=.13). When evaluating the overall study population, from both the healthcare sector and societal perspectives, midurethral sling surgery alone was superior to combined treatment. The probability that combined treatment is cost-effective compared with midurethral sling surgery alone is ≤28% from the healthcare sector and ≤19% from the societal perspectives for a willingness-to-pay value of ≤$150,000 per quality-adjusted life-years. For women with baseline Urogenital Distress Inventory irritative scores of ≥50th percentile, combined treatment was cost-effective compared with midurethral sling surgery alone from both the healthcare sector and societal perspectives. The probability that combined treatment is cost-effective compared with midurethral sling surgery alone for this subgroup is ≥90% from both the healthcare sector and societal perspectives, at a willingness-to-pay value of ≥$150,000 per quality-adjusted life-years.

Conclusion: Overall, perioperative behavioral and pelvic floor muscle therapies combined with midurethral sling surgery was not cost-effective compared with midurethral sling surgery alone for the treatment of women with mixed urinary incontinence. However, combined treatment was of good value compared with midurethral sling surgery alone for women with baseline severe urgency urinary incontinence symptoms.
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http://dx.doi.org/10.1016/j.ajog.2021.06.099DOI Listing
July 2021

Gating movements and ion permeation in HCN4 pacemaker channels.

Mol Cell 2021 07 23;81(14):2929-2943.e6. Epub 2021 Jun 23.

Department of Biosciences, University of Milan, Milan, Italy; Institute of Biophysics-Milano, Consiglio Nazionale delle Ricerche, Rome, Italy. Electronic address:

The HCN1-4 channel family is responsible for the hyperpolarization-activated cation current I/I that controls automaticity in cardiac and neuronal pacemaker cells. We present cryoelectron microscopy (cryo-EM) structures of HCN4 in the presence or absence of bound cAMP, displaying the pore domain in closed and open conformations. Analysis of cAMP-bound and -unbound structures sheds light on how ligand-induced transitions in the channel cytosolic portion mediate the effect of cAMP on channel gating and highlights the regulatory role of a Mg coordination site formed between the C-linker and the S4-S5 linker. Comparison of open/closed pore states shows that the cytosolic gate opens through concerted movements of the S5 and S6 transmembrane helices. Furthermore, in combination with molecular dynamics analyses, the open pore structures provide insights into the mechanisms of K/Na permeation. Our results contribute mechanistic understanding on HCN channel gating, cyclic nucleotide-dependent modulation, and ion permeation.
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http://dx.doi.org/10.1016/j.molcel.2021.05.033DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8294335PMC
July 2021

Fine Sampling of Sequence Space for Membrane Protein Structural Biology.

J Mol Biol 2021 07 20;433(15):167055. Epub 2021 May 20.

Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY 10032, USA. Electronic address:

We describe an enhancement of traditional genomics-based approaches to improve the success of structure determination of membrane proteins. Following a broad screen of sequence space to identify initial expression-positive targets, we employ a second step to select orthologs with closely related sequences to these hits. We demonstrate that a greater percentage of these latter targets express well and are stable in detergent, increasing the likelihood of identifying candidates that will ultimately yield structural information.
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http://dx.doi.org/10.1016/j.jmb.2021.167055DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8286341PMC
July 2021

Intermediates in allosteric equilibria of DnaK-ATP interactions with substrate peptides.

Acta Crystallogr D Struct Biol 2021 May 14;77(Pt 5):606-617. Epub 2021 Apr 14.

Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.

Hsp70 molecular chaperones facilitate protein disaggregation and proper folding through iterative cycles of polypeptide binding and release that are allosterically coupled to ATP binding and hydrolysis. Hsp70s are ubiquitous and highly conserved across all of life; they bind ATP at an N-terminal nucleotide-binding domain (NBD) and client peptides in the substrate-binding domain (SBD). The NBD and SBD are connected by a highly conserved linker segment that is integrated into the NBD when ATP is bound but is flexible when the NBD is nucleotide-free or bound with ADP. Allosteric coupling is lost when the linker is flexible, and the freed SBD binds peptide clients with high affinity. It was recently discovered that Hsp70-ATP is in an equilibrium between a restraining state (R) with little affinity for peptides and a low ATPase activity, and a stimulating state (S) that binds peptides efficiently, but with rapid kinetics, and has a relatively high ATPase activity. While attempting to characterize the S state, crystal structures of DnaK-ATP were obtained that demonstrate intrinsic Hsp70 plasticity that affects binding interactions with substrate peptides. These structures provide insights into intermediate states along transition pathways in the Hsp70 chaperone cycle.
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http://dx.doi.org/10.1107/S2059798321002436DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8098474PMC
May 2021
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