Magnetochrome: a c-type cytochrome domain specific to magnetotatic bacteria

2012 ◽  
Vol 40 (6) ◽  
pp. 1319-1323 ◽  
Author(s):  
Marina I. Siponen ◽  
Géraldine Adryanczyk ◽  
Nicolas Ginet ◽  
Pascal Arnoux ◽  
David Pignol
Keyword(s):  
Cytochrome C ◽  
Iron Acquisition ◽  
Magnetic Domain ◽  
Redox Potentials ◽  
Protein Sequence Analysis ◽  
Biophysical Characterization ◽  
Domain Specific ◽  
New Family ◽  
Periplasmic Proteins ◽  
Field Lines

Magnetotactic bacteria consist of a group of taxonomically, physiologically and morphologically diverse prokaryotes, with the singular ability to align with geomagnetic field lines, a phenomenon referred to as magnetotaxis. This magnetotactic property is due to the presence of iron-rich crystals embedded in lipidic vesicles forming an organelle called the magnetosome. Magnetosomes are composed of single-magnetic-domain nanocrystals of magnetite (Fe3O4) or greigite (Fe3S4) embedded in biological membranes, thereby forming a prokaryotic organelle. Four specific steps are described in this organelle formation: (i) membrane specialization, (ii) iron acquisition, (iii) magnetite (or greigite) biocrystallization, and (iv) magnetosome alignment. The formation of these magnetic crystals is a genetically controlled process, which is governed by enzyme-catalysed processes. On the basis of protein sequence analysis of genes known to be involved in magnetosome formation in Magnetospirillum magneticum AMB-1, we have identified a subset of three membrane-associated or periplasmic proteins containing a double cytochrome c signature motif CXXCH: MamE, MamP and MamT. The presence of these proteins suggests the existence of an electron-transport chain inside the magnetosome, contributing to the process of biocrystallization. We have performed heterologous expression in E. coli of the cytochrome c motif-containing domains of MamE, MamP and MamT. Initial biophysical characterization has confirmed that MamE, MamP and MamT are indeed c-type cytochromes. Furthermore, determination of redox potentials for this new family of c-type cytochromes reveals midpoint potentials of −76 and −32 mV for MamP and MamE respectively.

Avoidance of the cytochrome c biogenesis system by periplasmic CXXCH motifs

2008 ◽  
Vol 36 (6) ◽  
pp. 1124-1128 ◽  
Author(s):  
Despoina A.I. Mavridou ◽  
Martin Braun ◽  
Linda Thöny-Meyer ◽  
Julie M. Stevens ◽  
Stuart J. Ferguson
Keyword(s):  
Cytochrome C ◽  
Tertiary Structure ◽  
Evolutionary Relationship ◽  
Attachment Site ◽  
Cytochrome C Maturation ◽  
E Coli ◽  
Cytochrome C Biogenesis ◽  
Periplasmic Proteins ◽  
Bona Fide

The CXXCH motif is usually recognized in the bacterial periplasm as a haem attachment site in apocytochromes c. There is evidence that the Escherichia coli Ccm (cytochrome c maturation) system recognizes little more than the CXXCH sequence. A limited number of periplasmic proteins have this motif and yet are not c-type cytochromes. To explore how unwanted haem attachment to CXXCH might be avoided, and to determine whether haem attachment to the surface of a non-cytochrome protein would be possible, we converted the active-site CXXCK motif of a thioredoxin-like protein into CXXCH, the C-terminal domain of the transmembrane oxidoreductase DsbD (cDsbD). The E. coli Ccm system was found to catalyse haem attachment to a very small percentage of the resultant protein (∼0.2%). We argue that cDsbD folds sufficiently rapidly that only a small fraction fails to avoid the Ccm system, in contrast with bona fide c-type cytochromes that only adopt their tertiary structure following haem attachment. We also demonstrate covalent haem attachment at a low level in vivo to the periplasmic disulfide isomerase DsbC, which contains a native CXXCH motif. These observations provide insight into substrate recognition by the Ccm system and expand our understanding of the requirements for covalent haem attachment to proteins. The possible evolutionary relationship between thioredoxins and c-type cytochromes is discussed.

scholarly journals The Metallophore Staphylopine Enables Staphylococcus aureus To Compete with the Host for Zinc and Overcome Nutritional Immunity

mBio ◽  
2017 ◽  
Vol 8 (5) ◽  
Author(s):  
Kyle P. Grim ◽  
Brian San Francisco ◽  
Jana N. Radin ◽  
Erin B. Brazel ◽  
Jessica L. Kelliher ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Host Defense ◽  
Iron Acquisition ◽  
Essential Metals ◽  
Immune Effector ◽  
Essential Metal ◽  
Zinc Availability ◽  
Nutritional Immunity ◽  
New Family ◽  
New Type

ABSTRACT During infection, the host sequesters essential nutrients, such as zinc, to combat invading microbes. Despite the ability of the immune effector protein calprotectin to bind zinc with subpicomolar affinity, Staphylococcus aureus is able to successfully compete with the host for zinc. However, the zinc importers expressed by S. aureus remain unknown. Our investigations have revealed that S. aureus possesses two importers, AdcABC and CntABCDF, which are induced in response to zinc limitation. While AdcABC is similar to known zinc importers in other bacteria, CntABCDF has not previously been associated with zinc acquisition. Concurrent loss of the two systems severely impairs the ability of S. aureus to obtain zinc and grow in zinc-limited environments. Further investigations revealed that the Cnt system is responsible for the ability of S. aureus to compete with calprotectin for zinc in culture and contributes to acquisition of zinc during infection. The cnt locus also enables S. aureus to produce the broad-spectrum metallophore staphylopine. Similarly to the Cnt transporter, loss of staphylopine severely impairs the ability of S. aureus to resist host-imposed zinc starvation, both in culture and during infection. Further investigations revealed that together staphylopine and the Cnt importer function analogously to siderophore-based iron acquisition systems in order to facilitate zinc acquisition by S. aureus. Analogous systems are found in a broad range of Gram-positive and Gram-negative bacterial pathogens, suggesting that this new type of zinc importer broadly contributes to the ability of bacteria to cause infection. IMPORTANCE A critical host defense against infection is the restriction of zinc availability. Despite the subpicomolar affinity of the immune effector calprotectin for zinc, Staphylococcus aureus can successfully compete for this essential metal. Here, we describe two zinc importers, AdcABC and CntABCDF, possessed by S. aureus, the latter of which has not previously been associated with zinc acquisition. The ability of S. aureus to compete with the host for zinc is dependent on CntABCDF and the metallophore staphylopine, both in culture and during infection. These results expand the mechanisms utilized by bacteria to obtain zinc, beyond Adc-like systems, and demonstrate that pathogens utilize strategies similar to siderophore-based iron acquisition to obtain other essential metals during infection. The staphylopine synthesis machinery is present in a diverse collection of bacteria, suggesting that this new family of zinc importers broadly contributes to the ability of numerous pathogens to cause infection. IMPORTANCE A critical host defense against infection is the restriction of zinc availability. Despite the subpicomolar affinity of the immune effector calprotectin for zinc, Staphylococcus aureus can successfully compete for this essential metal. Here, we describe two zinc importers, AdcABC and CntABCDF, possessed by S. aureus, the latter of which has not previously been associated with zinc acquisition. The ability of S. aureus to compete with the host for zinc is dependent on CntABCDF and the metallophore staphylopine, both in culture and during infection. These results expand the mechanisms utilized by bacteria to obtain zinc, beyond Adc-like systems, and demonstrate that pathogens utilize strategies similar to siderophore-based iron acquisition to obtain other essential metals during infection. The staphylopine synthesis machinery is present in a diverse collection of bacteria, suggesting that this new family of zinc importers broadly contributes to the ability of numerous pathogens to cause infection.

scholarly journals Full assignment of heme redox potentials of cytochrome c 3 of D. vulgaris Miyazaki F by 1 H-NMR

FEBS Letters ◽  
1991 ◽  
Vol 285 (1) ◽  
pp. 149-151 ◽  
Author(s):  
Jang-Su Park ◽  
Katsuhiro Kano ◽  
Katsumi Niki ◽  
Hideo Akutsu
Keyword(s):  
Cytochrome C ◽  
Redox Potentials ◽  
H Nmr

scholarly journals The presence of two cytochromes b in the facultative methylotroph Pseudomonas AM1

1979 ◽  
Vol 180 (1) ◽  
pp. 237-239 ◽  
Author(s):  
C W Keevil ◽  
C Anthony
Keyword(s):  
Cytochrome C ◽  
Continuous Culture ◽  
Batch Culture ◽  
Growth Conditions ◽  
Redox Potentials ◽  
Deficient Mutant ◽  
Facultative Methylotroph

Two cytochromes b with absorption maxima at 555 and 562 nm and differing in their mid-point redox potentials are synthesized in Pseudomonas AM1 during growth on methanol or succinate in batch culture, or in NH4+-limited or carbon-limited continuous culture. Both cytochromes b were also present in a cytochrome c-deficient mutant in all growth conditions.

scholarly journals Recombinant Expression, Biophysical Characterization, and Cardiolipin-Induced Changes of Two Caenorhabditis elegans Cytochrome c Proteins

Biochemistry ◽  
2013 ◽  
Vol 52 (4) ◽  
pp. 653-666 ◽  
Author(s):  
Amber J. Vincelli ◽  
Danielle S. Pottinger ◽  
Fangfang Zhong ◽  
Jonas Hanske ◽  
Stéphane G. Rolland ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Cytochrome C ◽  
Recombinant Expression ◽  
Biophysical Characterization ◽  
C Proteins ◽  
Induced Changes

scholarly journals Assignment of the redox potentials to the four haems in Desulfovibrio vulgaris cytochrome c 3 by 2D-NMR

FEBS Letters ◽  
1992 ◽  
Vol 314 (2) ◽  
pp. 155-158 ◽  
Author(s):  
Carlos A. Salgueiro ◽  
David L. Turner ◽  
Helena Santos ◽  
Jean LeGall ◽  
António V. Xavier
Keyword(s):  
Cytochrome C ◽  
2D Nmr ◽  
Desulfovibrio Vulgaris ◽  
Redox Potentials
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