PhD: Cell, Molecular, and Developmental Biology

University of Alabama-Birmingham • 2010 — 2017

Indirect interactions affect the dynamics of multidrug resistance proteins and Sortase A

BSc: Biology

Gonzaga University • 2004 — 2008

Dean's List



Insubordinate • Jan 2018 — Present

I have completed the following projects and goals:

  • Created and deployed a version-controlled web journaling platform
  • Created and released a container-based development environment for building and deploying software (build-wrapper)
  • Created and released a containerized installation script and repository for JRiver Media Center (install_MC_fedora)
  • Learned php, sql, ruby, css, and html5 programming languages in addition to existing python, bash, tcl, and R knowledge
  • Contributed to open-source projects including ulauncher, fedora, podman, acme-dns, and openwrt
  • DIY renovated a home in the beautiful state of Florida
I am currently working on the following projects:
  • namd-python, a python wrapper for the NAMD molecular dynamics suite
  • oci-md, a k8s solution for cloud-based scientific software and job control
  • reso-wp, a RESO real estate API plugin for Wordpress
  • flre-wp, a web-based real estate IDX solution

University of Alabama at Birmingham

Graduate Research Assistant • Aug 2010 — Jan 2018

My doctoral thesis focused on the use of computational molecular dynamics to understand the impact of mutations and empirical structural determination methods on the function and dynamics of multidrug resistance (specifically, CFTR) and sortase proteins.

U.S. Census Bureau

Crew Leader • Jan 2010 — May 2010

Supervised a team of enumerators to ensure assigned tasks were completed properly. Monitored and evaluated performance for adjustments and improvements.


Roessler BC, Wei S, Icyuz M, Chauvet S, Tao B, Hartman JL 4th, Kirk KL.

FASEB J 30(3):1247-62 • March, 2016

Click for abstract

The ABCC transporter subfamily includes pumps, the long and short multidrug resistance proteins (MRPs), and an ATP-gated anion channel, the cystic fibrosis transmembrane conductance regulator (CFTR). We show that despite their thermodynamic differences, these ABCC transporter subtypes use broadly similar mechanisms to couple their extracellular gates to the ATP occupancies of their cytosolic nucleotide binding domains. A conserved extracellular phenylalanine at this gate was a prime location for producing gain of function (GOF) mutants of a long MRP in yeast (Ycf1p cadmium transporter), a short yeast MRP (Yor1p oligomycin exporter), and human CFTR channels. Extracellular gate mutations rescued ATP binding mutants of the yeast MRPs and CFTR by increasing ATP sensitivity. Control ATPase-defective MRP mutants could not be rescued by this mechanism. A CFTR double mutant with an extracellular gate mutation plus a cytosolic GOF mutation was highly active (single-channel open probability >0.3) in the absence of ATP and protein kinase A, each normally required for CFTR activity. We conclude that all 3 ABCC transporter subtypes use similar mechanisms to couple their extracellular gates to ATP occupancy, and highly active CFTR channels that bypass defects in ATP binding or phosphorylation can be produced.

Wang W, Roessler BC, Kirk KL.

J Biol Chem 289(44):30364-78 • October, 2014

Click for abstract

The CFTR channel is an essential mediator of electrolyte transport across epithelial tissues. CFTR opening is promoted by ATP binding and dimerization of its two nucleotide binding domains (NBDs). Phosphorylation of its R domain (e.g. by PKA) is also required for channel activity. The CFTR structure is unsolved but homology models of the CFTR closed and open states have been produced based on the crystal structures of evolutionarily related ABC transporters. These models predict the formation of a tetrahelix bundle of intracellular loops (ICLs) during channel opening. Here we provide evidence that residues E267 in ICL2 and K1060 in ICL4 electrostatically interact at the interface of this predicted bundle to promote CFTR opening. Mutations or a thiol modifier that introduced like charges at these two positions substantially inhibited ATP-dependent channel opening. ATP-dependent activity was rescued by introducing a second site gain of function (GOF) mutation that was previously shown to promote ATP-dependent and ATP-independent opening (K978C). Conversely, the ATP-independent activity of the K978C GOF mutant was inhibited by charge- reversal mutations at positions 267 or 1060 either in the presence or absence of NBD2. The latter result indicates that this electrostatic interaction also promotes unliganded channel opening in the absence of ATP binding and NBD dimerization. Charge-reversal mutations at either position markedly reduced the PKA sensitivity of channel activation implying strong allosteric coupling between bundle formation and R domain phosphorylation. These findings support important roles of the tetrahelix bundle and the E267-K1060 electrostatic interaction in phosphorylation-dependent CFTR gating.

Wei S, Roessler BC, Chauvet S, Guo J, Hartman JL 4th, Kirk KL.

J Biol Chem 289(29):19942-57 • July, 2014

Click for abstract

ATP-binding cassette (ABC) transporters are an ancient family of transmembrane proteins that utilize ATPase activity to move substrates across cell membranes. The ABCC subfamily of the ABC transporters includes active drug exporters (the multidrug resistance proteins (MRPs)) and a unique ATP-gated ion channel (cystic fibrosis transmembrane conductance regulator (CFTR)). The CFTR channel shares gating principles with conventional ligand-gated ion channels, but the allosteric network that couples ATP binding at its nucleotide binding domains (NBDs) with conformational changes in its transmembrane helices (TMs) is poorly defined. It is also unclear whether the mechanisms that govern CFTR gating are conserved with the thermodynamically distinct MRPs. Here we report a new class of gain of function (GOF) mutation of a conserved proline at the base of the pore-lining TM6. Multiple substitutions of this proline promoted ATP-free CFTR activity and activation by the weak agonist, 5'-adenylyl-β,γ-imidodiphosphate (AMP-PNP). TM6 proline mutations exhibited additive GOF effects when combined with a previously reported GOF mutation located in an outer collar of TMs that surrounds the pore-lining TMs. Each TM substitution allosterically rescued the ATP sensitivity of CFTR gating when introduced into an NBD mutant with defective ATP binding. Both classes of GOF mutations also rescued defective drug export by a yeast MRP (Yor1p) with ATP binding defects in its NBDs. We conclude that the conserved TM6 proline helps set the energy barrier to both CFTR channel opening and MRP-mediated drug efflux and that CFTR channels and MRP pumps utilize similar allosteric mechanisms for coupling conformational changes in their translocation pathways to ATP binding at their NBDs.

Huang P, Ho SR, Wang K, Roessler BC, Zhang F, Hu Y, Bowe DB, Kudlow JE, Paterson AJ.

Am J Physiol Cell Physiol. 300(3):C456-65 • March, 2011

Click for abstract

The protein O-linked β-N-acetylglucosamine (O-GlcNAc) modification plays an important role in skeletal muscle development and physiological function. In this study, bitransgenic mice were generated that overexpressed NCOAT(GK), an O-GlcNAcase-inactive spliced variant of the O-GlcNAcase gene, specifically in skeletal muscle using the muscle creatine kinase promoter. Expression of the chimeric enhanced green fluorescent protein-NCOAT(GK) transgene caused an increase of cellular O-GlcNAc levels, along with the accumulation and activation of proapoptotic factors in muscles of bitransgenic mice. The consequence of overexpressing the transgene for a 2-wk period was muscle atrophy and, in some cases, resulted in the death of male mice. Muscle atrophy is a common complication of many diseases, some of which correlate markedly with high cellular O-GlcNAc levels, such as diabetes. Our study provides direct evidence linking muscle atrophy and the disruption of O-GlcNAcase activity.


Similarities between the CFTR channel and MRP pumps.

CMDB/GGS Joint Seminar Series

Birmingham, AL • February 14, 2014

Computational and functional studies reveal similarities between the CFTR channel and ABC export pumps.

Frontiers in Structural Biology of Membrane Proteins International Symposium

Birmingham, AL • April 5, 2013

Molecular dynamics simulations of gating and rescue mechanisms in class IV CFTR mutants and other ABC transporters.

Student Physiology Seminar

Birmingham, AL • March 20, 2012

Published Abstracts & Posters

Conserved allosteric hot spots in the transmembrane domains of CFTR channels and MRP pumps.

Biomolecular Structure, Dynamics, and Function: Membrane Proteins

Vanderbilt University, Nashville, TN • May 2, 2014

Computational and functional experiments reveal similarities between the CFTR channel and MRP export pumps.

Abstracts of the 27th Annual North American Cystic Fibrosis Conference. Pediatric Pulmonology, 48 Suppl 36, 103-472.

Salt Lake City, UT • October 17-19, 2013

Insights into ABC transporter gating: Molecular dynamics simulations and a modular CFTR.

GBSO Student Retreat

Birmingham, AL • September 22, 2012

Grants, Honors, and Committees

University of Alabama at Birmingham

  • NIH T32 CMB Training Grant
  • Graduate Biomedical Sciences Outreach Committee

Gonzaga University

  • Dean’s List
  • Trustee Scholarship
  • Hooker Creek Endowed Scholarship


Molecular dynamics --- namd, vmd, gromacs, gaussian, charmm, amber

Languages --- python, php, sql, bash, tcl, R, css, html5, ruby, latex, git, gnuplot, matplotlib

Web frameworks --- jekyll, rails, hugo, django

Job control --- sge, slurm, pbs/torque

Linux sysadmin --- rhel & debian, systemd, podman/docker/oci, udev

Cloud admin --- k8s & openshift

Networking --- openwrt, pfsense, iptables, gpg

Graphics design

Outside Interests

  • Futurology, Automation & AI
  • Open-source Software
  • Computer Hardware
  • Fitness & Nutrition
  • E-Bikes
  • Pet Fostering
  • College Basketball (Go Zags!)

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