Characterization and Comparison of Metal Accumulation in Two <I>Escherichia coli</I> Strains Expressing Either CopA or MntA, Heavy Metal-Transporting Bacterial P-Type Adenosine Triphosphatases

Abstract

MntA from Lactobacillus plantarum and copA from Enterococcus hirae both encode membrane proteins that are members of the P-type family of adenosine triphosphatases (ATPases). Both transporters act as metal importers to take up nutritionally required substrates; MntA translocates Mn(II) and CopA translocates Cu(I). Both ATPases can also translocate secondary substrates, Cd(II) and Ag(I), respectively. Although functionally and sequentially similar, these ATPases differ in several key residues and in their membrane topologies. The bioaccumulation properties of these two proteins were examined by coexpressing the transporters with overexpressed metallothionein in Escherichia coli cells, a system that has previously shown high levels of substrate-specific uptake. Both strains exhibited rapid metal accumulation, both saturated at around 50 microM metal, and both displayed temperature-sensitive uptake. However, the transporters responded differently when external conditions were varied; MntA displayed increased sensitivity to ionic strength, while CopA was more pH sensitive and more inhibited by chelating agents. The differences in accumulation are likely owing to structural differences in the transmembrane region of these two ATPases.

Microalgal Metallothioneins and Phytochelatins and Their Potential Use in Bioremediation

“…Modified bacteria (Lactobacillus plantarum) and plants (T. caerulescens) exhibiting increased cellular proportions of primary active transporters were indeed found to uptake larger amounts of cadmium compared to the wild types (Deng et al, 2007;Ueno et al, 2011). Similarly, increased copper uptake rates were found in engineered Enterobacter hirae (Zagorski and Wilson, 2004). Since polyphosphate bodies are also known to bind metals (Wang and Dei, 2006), overexpression of polyphosphate kinases has been applied to improve mercury uptake (Kiyono et al, 2003).…”

Heavy Metal Removal by Bioaccumulation Using Genetically Engineered Microorganisms

“…For bioaccumulation, primary active transporters have been shown to import Cd and Cu. For Cd, MntA, and cdtB from Lactobacillus plantarum (Hao et al, 1999 ; Zagorski and Wilson, 2004 ; Kim et al, 2005 ; Deng et al, 2007 ; Kang et al, 2007 ) and TcHMA3 from the flowering plant Thlaspi caerulescens have been used in uptake (Chang and Shu, 2013 ). Bioaccumulation studies that used cdtB did not specify its accession number for a database query or any record of the DNA sequence.…”

“…These importers belong to the P-type ATPase superfamily (TCDB 3.A.3). For Cu, CopA from Enterobacter hirae has been used in uptake, which is also part of the P-type ATPase superfamily (Zagorski and Wilson, 2004 ).…”

A réz-efflux szabályzó CueR fehérje fémkötő sajátságainak tanulmányozása modellpeptideken keresztül

“…Ezt követően többféle módon kerülhetnek 6 be a citoszolba. Passzív transzporttal, például Nramp [6][7][8] és CorA [9] specifikus csatornák részvételével, valamint aktív transzporttal, ami transzmembrán fehérjéken vagy ATP függő ioncsatornák által (ABC típusú fehérjék [10,11], valamint P-típusú ATP-áz csatornák [12]) valósulhat meg.…”

“…A fémionok periplazmába, illetve a sejten kívüli térbe ürítéséről specifikus és nemspecifikus fehérjék gondoskodnak, mint például a P-típusú ATP függő transzportfehérjék [12], valamint egyéb membránfehérjék (Cation Diffusion Facilitators (CDFs) [19], továbbá RND (Resistance-Nodulation-cell Division) transzporter fehérjék [20]). [28][29][30][31][32] illetve a CsoR [33][34][35] család fehérjéi, valamint a réz és cink homeosztázisban fontos szerepet játszó CopY [36] és TetR [37] fehérjék).…”