Structure, Function and Formation of Bacterial Intracytoplasmic Membranes

Niederman, Robert A.

doi:10.1007/7171_025

Cited by 24 publications

(35 citation statements)

References 87 publications

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“…Our results favor previous suggestions arguing that the photosynthetic apparatus during greening is assembled in functional unit not in one step but in a sequential manner (Koblizek et al 2005;Niederman 2006). The major processes of photosynthetic complex assembly can be summarized in the following model (Fig.…”

Section: Cell-cycle-related Phenomenasupporting

confidence: 93%

Assembly of photosynthetic apparatus in Rhodobacter sphaeroides as revealed by functional assessments at different growth phases and in synchronized and greening cells

et al. 2014

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The development of photosynthetic membranes of intact cells of Rhodobacter sphaeroides was tracked by light-induced absorption spectroscopy and induction and relaxation of the bacteriochlorophyll fluorescence. Changes in membrane structure were induced by three methods: synchronization of cell growth, adjustment of different growth phases and transfer from aerobic to anaerobic conditions (greening) of the bacteria. While the production of the bacteriochlorophyll and carotenoid pigments and the activation of light harvesting and reaction center complexes showed cell-cycle independent and continuous increase with characteristic lag phases, the accumulation of phospholipids and membrane potential (electrochromism) exhibited stepwise increase controlled by cell division. Cells in the stationary phase of growth demonstrated closer packing and tighter energetic coupling of the photosynthetic units (PSU) than in their early logarithmic stage. The greening resulted in rapid (within 0-4 h) induction of BChl synthesis accompanied with a dominating role for the peripheral light harvesting system (up to LH2/LH1 ~2.5), significantly increased rate (~7·10(4) s(-1)) and yield (F v/F max ~0.7) of photochemistry and modest (~2.5-fold) decrease of the rate of electron transfer (~1.5·10(4) s(-1)). The results are discussed in frame of a model of sequential assembly of the PSU with emphasis on crowding the LH2 complexes resulting in an increase of the connectivity and yield of light capture on the one hand and increase of hindrance to diffusion of mobile redox agents on the other hand.

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Section: Cell-cycle-related Phenomenasupporting

confidence: 93%

Assembly of photosynthetic apparatus in Rhodobacter sphaeroides as revealed by functional assessments at different growth phases and in synchronized and greening cells

et al. 2014

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“…An intracytoplasmic membrane (ICM), which functions in the amplification of the cellular membrane content available for specific energy transduction processes, is found in a number of types of eubacteria (Niederman 2006). These species include anoxygenic chlorophototrophs of the a, b and c-proteobacterial subdivisions in which the ICM increases the surface available for the harvesting and utilization of radiant energy by means of one or more lightharvesting (LH) pigment-protein complexes and a type II photochemical reaction center (RC) (Hu et al 2002;Tavano and Donohue 2006).…”

Section: Introductionmentioning

confidence: 99%

Atomic force microscopy reveals multiple patterns of antenna organization in purple bacteria: implications for energy transduction mechanisms and membrane modeling

Sturgis

Niederman

2007

Photosynth Res

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Recent topographs of the intracytoplasmic membrane (ICM) of purple bacteria obtained by atomic force microscopy (AFM) have provided the first surface views of the native architecture of a multicomponent biological membrane at submolecular resolution, representing an important landmark in structural biology. A variety of species-dependent, closely packed arrangements of light-harvesting (LH) complexes was revealed: the most highly organized was found in Rhodobacter sphaeroides in which the peripheral LH2 antenna was seen either in large clusters or in fixed rows interspersed among ordered arrays of dimeric LH1-reaction center (RC) core complexes. A more random organization was observed in other species containing both the LH1 and LH2 complexes, as typified by Rhododspirillum photometricum with randomly packed monomeric LH1-RC core complexes intermingled with large, paracrystalline domains of LH2 antenna. Surprisingly, no structures that could be identified as the ATP synthase or cytochrome bc (1) complexes were observed, which may reflect their localization at ICM vesicle poles or in curved membrane areas, out of view from the flat regions imaged by AFM. This possible arrangement of energy transducing complexes has required a reassessment of energy tranduction mechanisms which place the cytochrome bc (1) complex in close association with the RC. Instead, more plausible proposals must account for the movement of quinone redox species over considerable membrane distances on appropriate time scales. AFM, together with atomic resolution structures are also providing the basis for molecular modeling of the ICM that is leading to an improved picture of the supramolecular organization of photosynthetic complexes, as well as the forces that drive their segregation into distinct domains.

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“…1 a). Extensive biochemical, biophysical and ultrastructural characterization of these membrane fractions [Niederman 2006;Tucker et al, 2010] have established that the UPB is enriched in nascent RC-LH1 core complexes, representing 'developing centers' [Koblízek et al, 2005]. These structures mature into fully formed photosynthetic units following further addition of LH2, which as membrane bending protein [Sturgis and Niederman, 1996] drives ICM vesiculation and ultimate budding of vesicles from the ICM continuum [Tucker et al, 2010].…”

Section: Isolation and Characterization Of Membranementioning

confidence: 99%

Structural and Functional Proteomics of Intracytoplasmic Membrane Assembly in <b><i>Rhodobacter sphaeroides</i></b>

et al. 2013

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The results of a detailed structural and functional proteomic analysis of intracytoplasmic membrane (ICM) assembly in the model purple phototrophic bacterium Rhodobacter sphaeroides are reviewed in this report. Proteomics approaches have focused upon identification of membrane proteins temporally expressed during ICM development and spatially localized within the internal cell membranes, together with their structural and functional correlates. For the examination of temporal protein expression, procedures were established for the induction of ICM formation at low oxygen tension and for ICM remodeling in cells adapting to low intensity illumination, which permitted isolation by rate-zone sedimentation of ICM growth initiation sites (CM invaginations) in an upper-pigmented band (UPB), together with more mature ICM vesicles (chromatophores) as the main band. Nondenaturing clear native gel electrophoresis of the chromatophore fraction gave rise to four pigmented bands: the top and bottom bands contained the reaction center-light-harvesting 1 (RC-LH1) core complex and the LH2 peripheral antenna, respectively, while two bands of intermediate migration exhibited distinct associations of LH2 and core complexes. Proteomic analysis of the gel bands revealed developmental changes including increasing levels of LH2 polypeptides relative to those of core complexes as ICM development proceeded, as well as a large array of other associated proteins including high spectral counts for the F₁F_O-ATP synthase subunits, and the cytochrome bc₁ complex. High counts were also observed for RSP6124, a protein of unknown function, that were correlated with increasing LH2 levels. RC-LH1-containing clear native electrophoresis gel bands from the UPB were enriched in cytoplasmic membrane (CM) markers, including electron transfer and transport proteins, as well as general membrane assembly factors (viz., preprotein translocases YidC, YajC and SecY, bacterial type 1 signal peptidase and twin arg translocation subunit TatA), thereby confirming the origin of the UPB from both peripheral respiratory membrane and sites of active CM invagination in which preferential assembly of the RC-LH1 complex occurs. Functional aspects of the photosynthetic unit assembly process were monitored by fluorescence induction/relaxation measurements of the variable fluorescence arising from LH-bacteriochlorophyll a. Slowing of the rate of RC electron transfer turnover (τ_QA), as assessed from the relaxation phase, was correlated with the growth of the functional absorption cross section (σ) and LH2/LH1 molar ratios. This is thought to arise from the imposition of constraints upon free diffusion of ubiquinone (UQ) redox species between the RC and cytochrome bc₁ complex as the ICM bilayer becomes densely packed with LH2 rings. Such LH2 packing was confirmed in a comparison by high-resolution atomic force microscopy of ICM patches from cells grown at high and low light intensity [Adams and Hunter: Biochim Biophys Act...

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Structure, Function and Formation of Bacterial Intracytoplasmic Membranes

Cited by 24 publications

References 87 publications

Assembly of photosynthetic apparatus in Rhodobacter sphaeroides as revealed by functional assessments at different growth phases and in synchronized and greening cells

Assembly of photosynthetic apparatus in Rhodobacter sphaeroides as revealed by functional assessments at different growth phases and in synchronized and greening cells

Atomic force microscopy reveals multiple patterns of antenna organization in purple bacteria: implications for energy transduction mechanisms and membrane modeling

Structural and Functional Proteomics of Intracytoplasmic Membrane Assembly in <b><i>Rhodobacter sphaeroides</i></b>

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