Koelper A

References (2)

Title : Fluorogenic structure activity library pinpoints molecular variations in substrate specificity of structurally homologous esterases - White_2018_J.Biol.Chem_293_13851
Author(s) : White A , Koelper A , Russell A , Larsen EM , Kim C , Lavis LD , Hoops GC , Johnson RJ
Ref : Journal of Biological Chemistry , 293 :13851 , 2018
Abstract : Cellular esterases catalyze many essential biological functions by performing hydrolysis reactions on diverse substrates. The promiscuity of esterases complicates assignment of their substrate preferences and biological functions. To identify universal factors controlling esterase substrate recognition, we designed a 32-member structure-activity relationship (SAR) library of fluorogenic ester substrates and used this library to systematically interrogate esterase preference for chain length, branching patterns, and polarity to differentiate common classes of esterase substrates. Two structurally homologous bacterial esterases were screened against this library, refining their previously broad overlapping substrate specificity. Vibrio cholerae esterase ybfF displayed a preference for gamma-position thioethers and ethers, whereas Rv0045c from Mycobacterium tuberculosis displayed a preference for branched substrates with and without thioethers. We determined that this substrate differentiation was partially controlled by individual substrate selectivity residues Tyr-119 in ybfF and His-187 in Rv0045c; reciprocal substitution of these residues shifted each esterase's substrate preference. This work demonstrates that the selectivity of esterases is tuned based on transition state stabilization, identifies thioethers as an underutilized functional group for esterase substrates, and provides a rapid method for differentiating structural isozymes. This SAR library could have multifaceted future applications, including in vivo imaging, biocatalyst screening, molecular fingerprinting, and inhibitor design.
ESTHER : White_2018_J.Biol.Chem_293_13851
PubMedSearch : White_2018_J.Biol.Chem_293_13851
PubMedID: 30006352
Gene_locus related to this paper: myctu-RV0045C , vibch-VC2097

Title : Measuring the Global Substrate Specificity of Mycobacterial Serine Hydrolases Using a Library of Fluorogenic Ester Substrates - Bassett_2018_ACS.Infect.Dis_4_904
Author(s) : Bassett B , Waibel B , White A , Hansen H , Stephens D , Koelper A , Larsen EM , Kim C , Glanzer A , Lavis LD , Hoops GC , Johnson RJ
Ref : ACS Infect Dis , 4 :904 , 2018
Abstract : Among the proteins required for lipid metabolism in Mycobacterium tuberculosis are a significant number of uncharacterized serine hydrolases, especially lipases and esterases. Using a streamlined synthetic method, a library of immolative fluorogenic ester substrates was expanded to better represent the natural lipidomic diversity of Mycobacterium. This expanded fluorogenic library was then used to rapidly characterize the global structure activity relationship (SAR) of mycobacterial serine hydrolases in M. smegmatis under different growth conditions. Confirmation of fluorogenic substrate activation by mycobacterial serine hydrolases was performed using nonspecific serine hydrolase inhibitors and reinforced the biological significance of the SAR. The hydrolases responsible for the global SAR were then assigned using gel-resolved activity measurements, and these assignments were used to rapidly identify the relative substrate specificity of previously uncharacterized mycobacterial hydrolases. These measurements provide a global SAR of mycobacterial hydrolase activity, a picture of cycling hydrolase activity, and a detailed substrate specificity profile for previously uncharacterized hydrolases.
ESTHER : Bassett_2018_ACS.Infect.Dis_4_904
PubMedSearch : Bassett_2018_ACS.Infect.Dis_4_904
PubMedID: 29648787