Assembly of Light-harvesting Bacteriochlorophyll in a Model Transmembrane Helix in its Natural Environment

Braun, Paula; Olsen, John D.; Strohmann, Brigitte; Hunter, C. Neil; Scheer, Hugo

doi:10.1016/s0022-2836(02)00192-4

Cited by 24 publications

(28 citation statements)

References 59 publications

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“…For the construction of the model BChl-binding sites, native residues of the BChl-B850 TM domains have been replaced by simplified alternating Ala-Leu stretches as described previously (32) (Fig. 1).…”

Section: Resultsmentioning

confidence: 99%

“…1). The Ala-Leu stretch, ␣AL, which replaces the BChl-B850 site in LH2-␣, extends over a stretch of 14 residues ranging from valine Ϫ7 3 at its N terminus to threonine ϩ6 at its C terminus (32). In LH2-␤, the Ala-Leu stretch, ␤AL, extends over 10 residues, ranging from glycine Ϫ7 to leucine ϩ2 (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In membranes containing ␣AL S Ϫ4-␤AL, the B800 transition is broadened to the blue side, and there is a shoulder at ϳ770 nm indicative of elevated amounts of "free" BChl, which points to defects in the assembly and/or stability of the complexes (Figs. 2 and 3A) (32). Quantitatively, less LH2 is assembled with ␣AL S Ϫ4-␤AL as compared with wt LH2 (and also to LH2 with ␣AL S Ϫ4-␤wt) as evaluated from the relative strength of the absorption bands in the nearly infrared and blue regions of the spectrum (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Construction of Mutant LH2-The construction of ␣AL has been carried as described previously (32). For the construction of ␤AL, pucB was subcloned into pGem4ϩ (Invitrogen) using an engineered HindIII site between pucB and pucA, just downstream of the stop codon of pucB, and a KpnI site upstream of the pucB coding region.…”

Section: Methodsmentioning

confidence: 99%

“…Preparation of Intracytoplasmic Membranes-The membranes were prepared from cells grown semi-aerobically in the dark by disruption in a French pressure cell and subsequent centrifugation on a sucrose step gradient (32).…”

Section: Methodsmentioning

confidence: 99%

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Hydrogen Bonding in a Model Bacteriochlorophyll-binding Site Drives Assembly of Light Harvesting Complex

Kwa¹,

García‐Martín²,

Végh

et al. 2004

Journal of Biological Chemistry

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In this study, the contribution of intramembrane hydrogen bonding at the interface between polypeptide and cofactor is explored in the native lipid environment by use of model bacteriochlorophyll proteins. In the peripheral antenna complex, LH2, large portions of the transmembrane helices, which make up the dimeric bacteriochlorophyll-binding site, are replaced by simplified, alternating alanine-leucine stretches. Replacement of either one of the two helices with the helices containing the model sequence at a time results in the assembly of complexes with nearly native light harvesting properties. In contrast, replacement of both helices results in the loss of antenna complexes from the membrane. The assembly of such doubly modified complexes is restored by a single intramembrane serine residue at position ؊4 relative to the liganding histidine of the ␣-subunit. In situ analysis of the spectral properties in a series of site-directed mutants reveals a critical dependence of the model complex assembly on the side chain of the residue at this position in the helix. A hydrogen bond between the hydroxy group of the serine and the 13 1 keto group of one of the central bacteriochlorophylls of the complexes is identified by Raman spectroscopy in the model antenna complex containing one of the alanine-leucine helices. The additional OH group of the serine residue, which participates in hydrogen bonding, increases the thermal stability of the model complexes in the native membrane. Intramembrane hydrogen bonding is thus shown to be a key factor for the binding of bacteriochlorophyll and assembly of this model cofactor-polypeptide site.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Hydrogen Bonding in a Model Bacteriochlorophyll-binding Site Drives Assembly of Light Harvesting Complex

Kwa¹,

García‐Martín²,

Végh

et al. 2004

Journal of Biological Chemistry

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In silico predictions of LH2 ring sizes from the crystal structure of a single subunit using molecular dynamics simulations

et al. 2011

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Most of the currently known light-harvesting complexes 2 (LH2) rings are formed by 8 or 9 subunits. As of now, questions like "what factors govern the LH2 ring size?" and "are there other ring sizes possible?" remain largely unanswered. Here, we investigate by means of molecular dynamics (MD) simulations and stochastic modeling the possibility of predicting the size of an LH2 ring from the sole knowledge of the high resolution crystal structure of a single subunit. Starting with single subunits of two LH2 rings with known size, that is, an 8-ring from Rs. moliscianum (MOLI) and a 9-ring from Rps. acidophila (ACI), and one with unknown size (referred to as X), we build atomic models of subunit dimers corresponding to assumed 8-, 9-, and 10-ring geometries. After inserting each of the dimers into a lipid-water environment, we determine the preferred angle between the corresponding subunits by three methods: (1) energy minimization, (2) free MD simulations, and (3) potential of mean force calculations. We find that the results from all three methods are consistent with each other, and when taken together, it allows one to predict with reasonable level of confidence the sizes of the corresponding ring structures. One finds that X and ACI very likely form a 9-ring, while MOLI is more likely to form an 8-ring than a 9-ring. Finally, we discuss both the merits and limitations of all three prediction methods.

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De Novo Protein Design in Respiration and Photosynthesis

Gibney

Tommos

2005

Advances in Photosynthesis and Respiration

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Assembly of Light-harvesting Bacteriochlorophyll in a Model Transmembrane Helix in its Natural Environment

Cited by 24 publications

References 59 publications

Hydrogen Bonding in a Model Bacteriochlorophyll-binding Site Drives Assembly of Light Harvesting Complex

Hydrogen Bonding in a Model Bacteriochlorophyll-binding Site Drives Assembly of Light Harvesting Complex

In silico predictions of LH2 ring sizes from the crystal structure of a single subunit using molecular dynamics simulations

De Novo Protein Design in Respiration and Photosynthesis

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