TY - JOUR
T1 - Structural and functional insights of GSU0105, a unique multiheme cytochrome from G. sulfurreducens
AU - Fernandes, Tomás M.
AU - Folgosa, Filipe
AU - Teixeira, Miguel
AU - Salgueiro, Carlos A.
AU - Morgado, Leonor
N1 - Funding Information:
info:eu-repo/grantAgreement/FCT/OE/SFRH%2FBD%2F145039%2F2019/PT#
info:eu-repo/grantAgreement/FCT/OE/SFRH%2FBPD%2F114848%2F2016/PT#
info:eu-repo/grantAgreement/FCT/3599-PPCDT/PTDC%2FBIA-BQM%2F31981%2F2017/PT#
info:eu-repo/grantAgreement/FCT/3599-PPCDT/PTDC%2FBIA-BQM%2F4967%2F2020/PT#
info:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UIDB%2F04378%2F2020/PT#
info:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UIDP%2F04378%2F2020/PT#
info:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UIDP%2F04612%2F2020/PT#
info:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UIDB%2F04612%2F2020/PT#
Prof. Dr. Derek R. Lovley (University of Massachusetts, Amherst) is acknowledged for providing the genomic DNA from G. sulfurreducens, Elisabete Ferreira (BioLab, UCIBIO, NOVA School of Science and Technology) for the technical assistance with the CD experiments, and Prof. Dr. David L. Turner and Prof. Dr. Pedro Tavares for the fruitful discussions. and. This work was also supported by 1) the Applied Molecular Biosciences Unit - UCIBIO, the project LA/P/0140/2020 of the Associate Laboratory Institute for Health and Bioeconomy i4HB; 3) the Instituto de Tecnologia Qu?mica e Biol?gica Ant?nio Xavier - Molecular, Structural and Cellular Microbiology Research Unit (ITQB-MOSTMICRO) (, co-funded by FCT, through national funds, and by Fundo Europeu de Desenvolvimento Regional (FEDER) under the PT2020 Partnership Agreement; and 4) the European Union's Horizon 2020 research and innovation program, under grant agreement 810856. The NMR spectrometers are part of the National NMR Network and are supported by FCT (ROTEIRO/0031/2013 and PINFRA/22161/2016) co-funded by FEDER through COMPETE 2020, Programa Operacional Ci?ncia e Inova??o (POCI), and Programa Operacional Regional de Lisboa (PORL) and FCT through Programa de Investimentos e Despesas de Desenvolvimento da Administra??o Central (PIDDAC).
Funding Information:
info:eu-repo/grantAgreement/FCT/OE/SFRH%2FBD%2F145039%2F2019/PT#
info:eu-repo/grantAgreement/FCT/OE/SFRH%2FBPD%2F114848%2F2016/PT#
info:eu-repo/grantAgreement/FCT/3599-PPCDT/PTDC%2FBIA-BQM%2F31981%2F2017/PT#
info:eu-repo/grantAgreement/FCT/3599-PPCDT/PTDC%2FBIA-BQM%2F4967%2F2020/PT
info:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UIDB%2F04378%2F2020/PT#
info:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UIDB%2F04612%2F2020/PT#
info:eu-repo/grantAgreement#
This work was also supported by 1) the Applied Molecular Biosciences Unit - UCIBIO, which is financed by national funds from FCT 2) the project LA/P/0140/2020 of the Associate Laboratory Institute for Health and Bioeconomy i4HB; 3) the Instituto de Tecnologia Química e Biológica António Xavier - Molecular, Structural and Cellular Microbiology Research Unit (ITQB-MOSTMICRO) and , co-funded by FCT , through national funds, and by Fundo Europeu de Desenvolvimento Regional ( FEDER) under the PT2020 Partnership Agreement; and 4) the European Union’s Horizon 2020 research and innovation program, under grant agreement 810856 . The NMR spectrometers are part of the National NMR Network and are supported by FCT ( ROTEIRO/0031/2013 and PINFRA/22161/2016 ) co-funded by FEDER through COMPETE 2020, Programa Operacional Ciência e Inovação ( POCI) , and Programa Operacional Regional de Lisboa (PORL) and FCT through Programa de Investimentos e Despesas de Desenvolvimento da Administração Central (PIDDAC).
Publisher Copyright:
© 2021 Biophysical Society
PY - 2021/12/7
Y1 - 2021/12/7
N2 - Geobacter sulfurreducens possesses over 100 cytochromes that assure an effective electron transfer to the cell exterior. The most abundant group of cytochromes in this microorganism is the PpcA family, composed of five periplasmic triheme cytochromes with high structural homology and identical heme coordination (His-His). GSU0105 is a periplasmic triheme cytochrome synthetized by G. sulfurreducens in Fe(III)-reducing conditions but is not present in cultures grown on fumarate. This cytochrome has a low sequence identity with the PpcA family cytochromes and a different heme coordination, based on the analysis of its amino acid sequence. In this work, amino acid sequence analysis, site-directed mutagenesis, and complementary biophysical techniques, including ultraviolet-visible, circular dichroism, electron paramagnetic resonance, and nuclear magnetic resonance spectroscopies, were used to characterize GSU0105. The cytochrome has a low percentage of secondary structural elements, with features of α-helices and β-sheets. Nuclear magnetic resonance shows that the protein contains three low-spin hemes (Fe(II), S = 0) in the reduced state. Electron paramagnetic resonance shows that, in the oxidized state, one of the hemes becomes high-spin (Fe(III), S = 5/2), whereas the two others remain low-spin (Fe(III), S = 1/2). The data obtained also indicate that the heme groups have distinct axial coordination. The apparent midpoint reduction potential of GSU0105 (−154 mV) is pH independent in the physiological range. However, the pH modulates the reduction potential of the heme that undergoes the low- to high-spin interconversion. The reduction potential values of cytochrome GSU0105 are more distinct compared to those of the PpcA family members, providing the protein with a larger functional working redox potential range. Overall, the results obtained, together with an amino acid sequence analysis of different multiheme cytochrome families, indicate that GSU0105 is a member of a new group of triheme cytochromes.
AB - Geobacter sulfurreducens possesses over 100 cytochromes that assure an effective electron transfer to the cell exterior. The most abundant group of cytochromes in this microorganism is the PpcA family, composed of five periplasmic triheme cytochromes with high structural homology and identical heme coordination (His-His). GSU0105 is a periplasmic triheme cytochrome synthetized by G. sulfurreducens in Fe(III)-reducing conditions but is not present in cultures grown on fumarate. This cytochrome has a low sequence identity with the PpcA family cytochromes and a different heme coordination, based on the analysis of its amino acid sequence. In this work, amino acid sequence analysis, site-directed mutagenesis, and complementary biophysical techniques, including ultraviolet-visible, circular dichroism, electron paramagnetic resonance, and nuclear magnetic resonance spectroscopies, were used to characterize GSU0105. The cytochrome has a low percentage of secondary structural elements, with features of α-helices and β-sheets. Nuclear magnetic resonance shows that the protein contains three low-spin hemes (Fe(II), S = 0) in the reduced state. Electron paramagnetic resonance shows that, in the oxidized state, one of the hemes becomes high-spin (Fe(III), S = 5/2), whereas the two others remain low-spin (Fe(III), S = 1/2). The data obtained also indicate that the heme groups have distinct axial coordination. The apparent midpoint reduction potential of GSU0105 (−154 mV) is pH independent in the physiological range. However, the pH modulates the reduction potential of the heme that undergoes the low- to high-spin interconversion. The reduction potential values of cytochrome GSU0105 are more distinct compared to those of the PpcA family members, providing the protein with a larger functional working redox potential range. Overall, the results obtained, together with an amino acid sequence analysis of different multiheme cytochrome families, indicate that GSU0105 is a member of a new group of triheme cytochromes.
UR - http://www.scopus.com/inward/record.url?scp=85118926432&partnerID=8YFLogxK
U2 - 10.1016/j.bpj.2021.10.023
DO - 10.1016/j.bpj.2021.10.023
M3 - Article
C2 - 34688593
AN - SCOPUS:85118926432
SN - 0006-3495
VL - 120
SP - 5395
EP - 5407
JO - Biophysical Journal
JF - Biophysical Journal
IS - 23
ER -