The alternative complex III from Rhodothermus marinus - a prototype of a new family of quinol: electron acceptor oxidoreductase

Dissertation presented to obtain a PhD degree in Biochemistry at the Instituto de Tecnologia Química e Biológica, Universidade Nova de LisboaThe aim of the work presented in this thesis was the characterization of a complex with quinol: electron carrier oxidodoreductase activity present in the membranes of the thermohalophilic bacterium Rhodothermus (R.) marinus. The complexes involved in the R. marinus respiratory chain have been extensively studied in the past few years. Specifically, the purification and characterization of a complex I (NADH: quinone oxidoreductase), a complex II (succinate:quinone oxidoreductase) and of three different oxygen reductases from the heme-copper oxygen reductases superfamily have been performed. Since those oxygen reductases are unable to receive electrons from quinol molecules, the presence of a complex linking complexes I and II to the oxygen reductases was needed. In fact, a complex with quinol: HiPIP oxidoreductase activity was purified and partially characterized. The absence of the Rieske protein indicated that the complex isolated from R. marinus has a different composition when compared with the typical cytochrome bc1 complex.(...

The alternative complex III of Rhodothermus marinus and its structural and functional association with caa3 oxygen reductase

AbstractAn alternative complex III (ACIII) is a respiratory complex with quinol:electron acceptor oxidoreductase activity. It is the only example of an enzyme performing complex III function that does not belong to bc1 complex family. ACIII from Rhodothermus (R.) marinus was the first enzyme of this type to be isolated and characterized, and in this work we deepen its characterization. We addressed its interaction with quinol substrate and with the caa3 oxygen reductase, whose coding gene cluster follows that of the ACIII. There is at least, one quinone binding site present in R. marinus ACIII as observed by fluorescence quenching titration of HQNO, a quinone analogue inhibitor. Furthermore, electrophoretic and spectroscopic evidences, taken together with mass spectrometry revealed a structural association between ACIII and caa3 oxygen reductase. The association was also shown to be functional, since quinol:oxygen oxidoreductase activity was observed when the two isolated complexes were put together. This work is thus a step forward in the recognition of the structural and functional diversities of prokaryotic respiratory chains

Quinone oxidoreductase from Staphylococcus aureus

Funding Information: Helena Gaspar is acknowledged for the HPLC analyses and Bruno Victor for advice on modelling. F.M.S. and M.S.S. are recipients of fellowships by Fundação para a Ciência e a Tecnologia (PD/BD/128213/2016 and PD/BD/128202/2016, respectively, both within the scope of the PhD program Molecular Biosciences PD/00133/2012). A.B. is recipient of a fellowship by Fundação para a Ciência e a Tecnologia UI/BD/153052/2022. The work was funded by Fundação para a Ciência e a Tecnologia ( PTDC/BIA-BQM/2599/2021 to M.M.P). The project was further supported by UIDB/04046/2020 and UIDP/04046/2020 Centre grants from FCT , Portugal (to BioISI), by LISBOA-01-0145-FEDER-007660 cofunded by FEDER through COMPETE2020-POCI and by Fundação para a Ciência e a Tecnologia and by UIDB/04612/2020 and UIDP/04612/2020 research unit grants from FCT (to Mostmicro). The NMR spectrometers are part of the National NMR Network (PTNMR) and are supported by Infrastructure Project N° 022161 (co-financed by FEDER through COMPETE 2020, POCI, and PORL and FCT through PIDDAC). Funding Information: Helena Gaspar is acknowledged for the HPLC analyses and Bruno Victor for advice on modelling. F.M.S. and M.S.S. are recipients of fellowships by Fundação para a Ciência e a Tecnologia (PD/BD/128213/2016 and PD/BD/128202/2016, respectively, both within the scope of the PhD program Molecular Biosciences PD/00133/2012). A.B. is recipient of a fellowship by Fundação para a Ciência e a Tecnologia UI/BD/153052/2022. The work was funded by Fundação para a Ciência e a Tecnologia (PTDC/BIA-BQM/2599/2021 to M.M.P). The project was further supported by UIDB/04046/2020 and UIDP/04046/2020 Centre grants from FCT, Portugal (to BioISI), by LISBOA-01-0145-FEDER-007660 cofunded by FEDER through COMPETE2020-POCI and by Fundação para a Ciência e a Tecnologia and by UIDB/04612/2020 and UIDP/04612/2020 research unit grants from FCT (to Mostmicro). The NMR spectrometers are part of the National NMR Network (PTNMR) and are supported by Infrastructure Project N° 022161 (co-financed by FEDER through COMPETE 2020, POCI, and PORL and FCT through PIDDAC). Publisher Copyright: © 2022 The Author(s)Staphylococcus aureus is an opportunistic pathogen and one of the most frequent causes for community acquired and nosocomial bacterial infections. Even so, its energy metabolism is still under explored and its respiratory enzymes have been vastly overlooked. In this work, we unveil the dihydroorotate:quinone oxidoreductase (DHOQO) from S. aureus, the first example of a DHOQO from a Gram-positive organism. This protein was shown to be a FMN containing menaquinone reducing enzyme, presenting a Michaelis-Menten behaviour towards the two substrates, which was inhibited by Brequinar, Leflunomide, Lapachol, HQNO, Atovaquone and TFFA with different degrees of effectiveness. Deletion of the DHOQO coding gene (Δdhoqo) led to lower bacterial growth rates, and effected in cell morphology and metabolism, most importantly in the pyrimidine biosynthesis, here systematized for S. aureus MW2 for the first time. This work unveils the existence of a functional DHOQO in the respiratory chain of the pathogenic bacterium S. aureus, enlarging the understanding of its energy metabolism.publishersversionpublishe

Structural basis for energy transduction by respiratory alternative complex III

Some prokaryotes use alternative respiratory chain complexes, such as the alternative complex III (ACIII), to generate energy. Here authors provide the cryoEM structure of ACIII from Rhodothermus marinus which shows the arrangement of cofactors and provides insights into the mechanism for energy transduction