Structural Basis for the Thermostability of Ferredoxin from the Cyanobacterium Mastigocladus laminosus

Fish, Alexander; Danieli, Tsafi; Ohad, Itzhak; Nechushtai, Rachel; Livnah, Oded

doi:10.1016/j.jmb.2005.04.071

Cited by 37 publications

(47 citation statements)

References 57 publications

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“…Despite the minimal effect that L1,2 deletion has on the tertiary structure, this deletion maintains activity well below the optimal temperature of the thermophilic organism but abolishes the electron transport properties of this protein in vitro at 55°C (19). Electron transport efficiencies are the result of a combination of intra-and interprotein interactions and properties including distance, orientation, hydrogen bonding, van der Waals, electrostatic interactions, and folding characteristics.…”

Section: Resultsmentioning

confidence: 99%

“…This Fdx folding motif is among the most abundant in nature, and it has been well studied previously biochemically (18)(19)(20)(21)(22)(23), making Fdx an excellent candidate for quantitative, biophysical characterization. Moreover, the planttype Fdx folding motif has been found in numerous redox proteins and enzymes, as well as in functionally unrelated proteins that do not contain the [2Fe-2S] cluster, such as ubiquitin and the immunoglobulin-binding domain of protein G (24,25).…”

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confidence: 99%

“…These proteins are key players in the three life-essential processes: photosynthesis, nitrogen fixation, and respiration (29,30). The plant-type Fdx proteins carry a single surface-exposed [2Fe-2S] iron-sulfur cluster (ISC) (19), and homologous proteins are found in all organisms, e.g., adrenodoxin in human mitochondria (20). The oxidation-reduction potentials (E m ) of these Fdx proteins range from −325 mV to around −450 mV (21), making Fdx one of the strongest soluble reducing agents in nature (22).…”

mentioning

confidence: 99%

“…Substitution of the flexible L1,2 loop (residues 10-14) of wild-type Fdx (mFdx WT ) with the rigid β-turn of a mesophilic Fdx (residues 10-12) (here we refer to this substituted mutant as mFdx ΔL1;2 ),* yields a protein that is functional at 23°C but loses electron-transfer (ET) activity at 55°C (19), whereas mFdx is fully active. This loss of function is not due to dissociation of the [2Fe-2S] cluster, as this moiety is stable to 75°C.…”

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confidence: 99%

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Allostery in the ferredoxin protein motif does not involve a conformational switch

Nechushtai

Lammert²,

Michaeli³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Regulation of protein function via cracking, or local unfolding and refolding of substructures, is becoming a widely recognized mechanism of functional control. Oftentimes, cracking events are localized to secondary and tertiary structure interactions between domains that control the optimal position for catalysis and/or the formation of protein complexes. Small changes in free energy associated with ligand binding, phosphorylation, etc., can tip the balance and provide a regulatory functional switch. However, understanding the factors controlling function in single-domain proteins is still a significant challenge to structural biologists. We investigated the functional landscape of a single-domain planttype ferredoxin protein and the effect of a distal loop on the electron-transfer center. We find the global stability and structure are minimally perturbed with mutation, whereas the functional properties are altered. Specifically, truncating the L1,2 loop does not lead to large-scale changes in the structure, determined via X-ray crystallography. Further, the overall thermal stability of the protein is only marginally perturbed by the mutation. However, even though the mutation is distal to the iron-sulfur cluster (∼20 Å), it leads to a significant change in the redox potential of the ironsulfur cluster (57 mV). Structure-based all-atom simulations indicate correlated dynamical changes between the surface-exposed loop and the iron-sulfur cluster-binding region. Our results suggest intrinsic communication channels within the ferredoxin fold, composed of many short-range interactions, lead to the propagation of long-range signals. Accordingly, protein interface interactions that involve L1,2 could potentially signal functional changes in distal regions, similar to what is observed in other allosteric systems.electron transfer | functional energy landscape | iron-sulfur proteins | protein folding O ver the last several decades, our understanding of protein function has evolved from a rather static perspective, where signaling and function have been understood through surface complementarity arguments, such as the "lock and key" paradigm (1, 2), to a more dynamic view where protein conformational fluctuations are inextricably linked to function (3). As our understanding of protein dynamics expands, we are revealing many mechanisms by which proteins exploit conformational fluctuations to perform cellular function. In multidomain proteins, relative repositioning of domains is often linked to their levels of activity. For example, large-scale domain rearrangements in the four-domain Src kinase (4) and C-terminal Src kinase (5, 6) lead to these proteins being in so-called "on" or "off" states, and functional regulation may be obtained by adjusting the balance between these conformations (7). In proteins such as adenylate kinase, domain rearrangements can be rate limiting during each round of catalysis (8), where the enzyme cycles between ligandcompetent and ligand-release conformations. Because the kinetics of these tra...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Allostery in the ferredoxin protein motif does not involve a conformational switch

Nechushtai

Lammert²,

Michaeli³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…gliding of its hormogonia through agar (ROBINSON et al 2007), and production of capsular polysaccharides and their anti-cancer activity (GLOAGUEN et al 1999(GLOAGUEN et al , 2007. It is also interesting that its ferredoxin activity was optimal at 65°C (FISH et al 2005), but the alga was shown to grow as a branched form at <53°C, and unbranched form in 60°C (CASTENHOLZ 1972). M. laminosus has been demonstrated as a pioneer species for a laboratory model of cyanobacterial mat (BRYANSKAYA et al 2008).…”

Section: Notesmentioning

confidence: 99%

Cyanobacteria of the thermal spring at Pancharevo, Sofia, Bulgaria

Lukavský¹,

Furnadzhieva²,

Пиларски³

2011

Acta Botanica Croatica

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-Eight taxa of cyanobacteria were identified in the thermal spring at Pancharevo (in the Sofia basin, Bulgaria). As well as the widespread Lyngbya thermalis, Phormidesmis molle (syn. Phormidium molle), Phormidium papyraceum, Phormidium corium and Mastigocladus laminosus, four species were identified for the first time in Bulgaria: Calothrix thermalis, Gloeocapsa gelatinosa, Leibleinia epiphytica and Symploca thermalis.

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Ferredoxin and Flavodoxin Mediated Electron Transfer in Photosystem I

Fromme

2008

Photosynthetic Protein Complexes

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Structural Basis for the Thermostability of Ferredoxin from the Cyanobacterium Mastigocladus laminosus

Cited by 37 publications

References 57 publications

Allostery in the ferredoxin protein motif does not involve a conformational switch

Allostery in the ferredoxin protein motif does not involve a conformational switch

Cyanobacteria of the thermal spring at Pancharevo, Sofia, Bulgaria

Ferredoxin and Flavodoxin Mediated Electron Transfer in Photosystem I

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