The P-type ATPase CtpG preferentially transports Cd2+ across the Mycobacterium tuberculosis plasma membrane

Abstract

P-type ATPases are involved in heavy metal transport across the plasma membrane. Some Mycobacterium tuberculosis P-type ATPases are induced during infection, suggesting that this type of transporter could play a critical role in mycobacterial survival. To date, the ion specificity of M. tuberculosis heavy metal-transporting P-ATPases is not well understood. In this work, we observed that, although divalent heavy metal cations such as Cu, Co, Ni, Zn Cd and Pb stimulate the ATPase activity of the putative P-type ATPase CtpG in the plasma membrane, whole cells of M. smegmatis expressing CtpG only tolerate high levels of Cd and Cu. As indicator of the catalytic constant, Michaelis-Menten kinetics showed that CtpG embedded in the mycobacterial cell membrane has a V /K ratio 7.4-fold higher for Cd than for Cu ions. Thus, although CtpG can accept different substrates in vitro, this P-type ATPase transports Cd more efficiently than other heavy metal cations across the mycobacterial plasma membrane.

CtpB is a plasma membrane copper (I) transporting P-type ATPase of Mycobacterium tuberculosis

“…This optimal temperature is similar to the average temperature of the human body, which in turn is the natural host of M. tuberculosis. Similarly, the observed optimal pH (7.4) is close to neutrality, as well as the observed for other mycobacterial P-type ATPases [35][36][37]. Finally, CtpB displayed a concentration-dependent Cu + ATPase activity when the enzymatic reaction was supplemented with Cys at concentrations below 0.5 mM.…”

“…Bacterial tolerance against toxic concentrations of metal cations mediated by P-type ATPases has been previously reported in mycobacteria. For example, recombinant M. smegmatis cells overexpressing the putative M. tuberculosis cadmium transporter CtpG tolerate high doses of Cd 2+ compared with non-recombinant mycobacterial cells [36]. Similarly, M. smegmatis homologously expressing the putative alkali/alkaline earth cation P-type ATPase transporter Pma1 tolerates toxic concentrations of Na + , K + , and Na + /K + ions [37].…”

“…Since there is a contribution to the ATPase activity from other cell-membrane ATPases, parallel enzymatic reactions using membranes from M. smegmatis mc 2 155 transformed with the empty vector pMV261 were used as control. Therefore, the enzymatic activity mediated by CtpB was calculated by subtracting the ATPase activity of the control membranes from the ATPase activity of the recombinant membranes [35][36][37]. Using this experimental approach, it was observed that Cu + was the only cation that significantly stimulated the ATPase activity of CtpB embedded in the mycobacterial plasma membrane, compared with other divalent heavy metal cations (Fig.…”

Genome-wide Identification and Function Analysis of HMAD Gene Family in Cotton (Gossypium Spp.)

“…CtpB, as a plasma membrane copper (I) transporting P-type ATPase of Mycobacterium tuberculosis, is different from copper detoxi cation [77]. In Mycobacterium tuberculosis, Cu 2+ , Co 2+ , Ni 2+ , Zn 2+ , Cd 2+ and Pb 2+ stimulate the ATPase activity of the putative P1B-type ATPase CtpG in the plasma membrane, while Cd 2+ more e ciently than other heavy metal cations across the mycobacterial plasma membrane [78]. Chaperone is an important way in delivering Cu to heavy metal P1B-ATPases [41].…”

Mycolicibacterium smegmatis, Basonym Mycobacterium smegmatis, Expresses Morphological Phenotypes Much More Similar to Escherichia coli Than Mycobacterium tuberculosis in Quantitative Structome Analysis and CryoTEM Examination

“…Mycolicibacterium smegmatis is a rapid-growing bacterium and previously belonged to the genus Mycobacterium as basonym Mycobacterium smegmatis , to which many pathogenic mycobacteria, including M. tuberculosis , a causative agent of tuberculosis, and M. leprae , a causative agent of leprosy, are belonging (Gupta et al, 2018 ; Oren and Garrity, 2018 ). Therefore, M. smegmatis has been quite often used as substitute for M. tuberculosis or M. leprae in studies, especially in the field of molecular biology, and there are a number of literature (Bashiri and Baker, 2015 ; Brown-Elliott and Philley, 2017 ), more than 15 papers, listed only in 2018 (Angara et al, 2018 ; Burian and Thompson, 2018 ; Chandran et al, 2018 ; Chen et al, 2018 ; Dal Molin et al, 2018 ; Ghosh et al, 2018 ; Goins et al, 2018 ; Jesus et al, 2018 ; Kaur et al, 2018 ; Kumar et al, 2018 ; Lopez et al, 2018 ; Marney et al, 2018 ; Mortuza et al, 2018 ; Richards et al, 2018 ; Singh et al, 2018 ; Tsaloglou et al, 2018 ; Verma et al, 2018 ).…”