Regulation of Structural Protein Interactions as Revealed in Phage Morphogenesis

King, Jonathan

doi:10.1007/978-1-4684-9933-9_3

Cited by 27 publications

(11 citation statements)

References 80 publications

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“…If the coat behaves as an elastic material, then coat protein monomers must be synthesized in a relatively high-energy state and the spring-like nature of the coat appears only after assembly is largely or entirely complete. The notion that, prior to dehydration, the coat is in a metastable state brings to mind the assembly of the tail sheath of bacteriophage T4 (26). The view that the coat is flexible, along with a recent study by Westphal et al (53; see also reference 10), may help account for a type of variability commonly seen in thin-section electron micrographs of spores; typical fields show spores in which the ridge number and shape varies significantly.…”

Section: Discussionmentioning

confidence: 99%

Morphogenesis of Bacillus Spore Surfaces

et al. 2003

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Spores produced by bacilli are encased in a proteinaceous multilayered coat and, in some species (including Bacillus anthracis), further surrounded by a glycoprotein-containing exosporium. To characterize bacillus spore surface morphology and to identify proteins that direct formation of coat surface features, we used atomic-force microscopy (AFM) to image the surfaces of wild-type and mutant spores of Bacillus subtilis, as well as the spore surfaces of Bacillus cereus 569 and the Sterne strain of Bacillus anthracis. This analysis revealed that the coat surfaces in these strains are populated by a series of bumps ranging between 7 and 40 nm in diameter, depending on the species. Furthermore, a series of ridges encircled the spore, most of which were oriented along the long axis of the spore. The structures of these ridges differ sufficiently between species to permit species-specific identification. We propose that ridges are formed early in spore formation, when the spore volume likely decreases, and that when the spore swells during germination the ridges unfold. AFM analysis of a set of B. subtilis coat protein gene mutants revealed three coat proteins with roles in coat surface morphology: CotA, CotB, and CotE. Our data indicate novel roles for CotA and CotB in ridge pattern formation. Taken together, these results are consistent with the view that the coat is not inert. Rather, the coat is a dynamic structure that accommodates changes in spore volume.

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Section: Discussionmentioning

confidence: 99%

Morphogenesis of Bacillus Spore Surfaces

et al. 2003

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“…If such ordered interactions can produce something as complicated as the phage contractile tail 58; 59 or the bacterial flagellum 60 , then the related scheme that we suggest should be able to control the shape of a capsid. Berget 61 and King 62 have discussed such mechanisms in detail for sequential assembly of different proteins, which King called self-regulated assembly , “in which polymerization is regulated through the interactions of free subunits with an organized structure.”…”

Section: Discussionmentioning

confidence: 99%

Transient Contacts on the Exterior of the HK97 Procapsid That Are Essential for Capsid Assembly

Tso¹,

Hendrix²,

Duda³

2014

Journal of Molecular Biology

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The G-loop is a 10-residue glycine-rich loop that protrudes from the surface of the mature bacteriophage HK97 capsid at the C-terminal end of the long backbone helix of major capsid protein subunits. The G-loop is essential for assembly, is conserved in related capsid and encapsulin proteins, and plays its role during HK97 capsid assembly by making crucial contacts between the hill-like hexamers and pentamers in precursor proheads. These contacts are not preserved in the flattened capsomers of the mature capsid. Aspartate 231 in each of the ~400 G-loops interacts with Lysine 178 of the E-loop (Extended Loop) of a subunit on an adjacent capsomer. Mutations disrupting this interaction prevented correct assembly, and in some cases induced abnormal assembly into tubes, or small, incomplete capsids. Assembly remained defective when D231 and K178 were replaced with larger charged residues or when their positions were exchanged. Second-site suppressors of lethal mutants containing substitution D231L replaced the ionic interaction with new interactions between neutral or hydrophobic residues of about the same size: D231L/K178V, D231L/K178I, and D231L/K178N. We conclude that it is not the charge, but the size and shape of the side chains of residues 178 and 231 that are important. These two residues control the geometry of contacts between the E-loop and the G-loop, which apparently must be precisely spaced and oriented for correct assembly to occur. We present a model for how the G-loop could control HK97 assembly and identify G-loop-like protrusions in other capsid proteins that may play analogous roles.

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“…Conditional mutants have been used as a tool in the dissection of the genetic and biochemical events involved in many cellular processes, including phage morphogenesis and eucaryotic cell division (22,35 Fig. 6 may reflect decreased dosage of a gene product that, over time, is compensated for by the homologous gene on the remaining chromosome III.…”

Section: Discussionmentioning

confidence: 99%

Genetic manipulation of centromere function.

Hill¹,

Bloom²

1987

Mol. Cell. Biol.

198

195

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A conditional centromere was constructed in Saccharomyces cerevisiae by placing the centromere of chromosome III immediately downstream from the inducible GAL) promoter from S. cerevisiae. By utilizing growth conditions that favor either transcriptional induction (galactose-carbon source) or repression (glucosecarbon source) from the GAL) promoter, centromere function can be switched off or on, respectively. With the conditional centromere we were able to radically alter the mitotic transmission pattern of both monocentric and dicentric plasmids. Moreover, it was possible to selectively induce the loss of a single chromosome from a mitoticafly dividing population of cells. We observed that the induction of chromosome HI aneuploidy resulted in a dramatic change in cell morphology. The construction of a conditional centromere represents a novel way to create conditional mutations of cis-acting DNA elements and will be useful for further analysis of this important stabilizing element.Chromosome segregation in most eucaryotic organisms involves the attachment of a spindle apparatus to a specific chromosomal domain, the kinetochore. While the assembly and disassembly of the mitotic spindle can be visualized by a variety of methods, the mechanism by which chromosomes become attached to this apparatus is not understood. The isolation of the DNA sequences required for chromosome segregation in the budding yeast Saccharomyces cerevisiae has provided the first insights at the molecular level into the function of this unique chromosomal domain (7,12,13,18,24,30,34,38).There are two major components involved in chromosomal segregation: the spindle apparatus and the kinetochore. The spindle apparatus provides the framework for chromosome movement in mitosis through spindle fibers that are connected to the chromosomes. The kinetochore includes the structural components at the site of attachment of the spindle fibers and is located within a unique chromosomal domain, the centromere. During mitosis, the centromere region is observed as the primary constriction along the chromosome fiber in higher eucaryotic cells. The centromeric region in the yeast cannot be seen microscopically due to the absence of mitotic chromosome condensation in S. cerevisiae. Examination of the molecular structure of yeast centromeres by nuclease digestion has revealed that centromeric DNA (CEN) is organized into a 220-to 250-base-pair (bp) protected chromatin structure (4). The centromere core particle, including DNA and associated protein, is therefore structurally distinct from the typical 146-bp DNA-histone core particle that constitutes the bulk of eucaryotic chromatin. Centromere DNA, whether in situ, in heterologous chromosomes or in autonomously replicating plasmids introduced into yeast, is always organized into a 220-to 250-bp core complex (3). Furthermore, point mutations at select sites within this region result in both inactivation of centromere function (28) and complete disruption of the protected chromatin core (M. J. Saunders and K. S. ...

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Regulation of Structural Protein Interactions as Revealed in Phage Morphogenesis

Cited by 27 publications

References 80 publications

Morphogenesis of Bacillus Spore Surfaces

Morphogenesis of Bacillus Spore Surfaces

Transient Contacts on the Exterior of the HK97 Procapsid That Are Essential for Capsid Assembly

Genetic manipulation of centromere function.

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