The Role of Minor Pilins in Assembly and Function of the Competence Pilus of Streptococcus pneumoniae

The remarkable genomic plasticity of Streptococcus pneumoniae largely depends on its ability to undergo natural genetic transformation. To take up extracellular DNA, S. pneumoniae assembles competence pili composed of the major pilin ComGC. In addition to ComGC, four minor pilins ComGD, E, F, and G are expressed during bacterial competence, but their role in pilus biogenesis and transformation is unknown. Here, using a combination of protein-protein interaction assays we show that all four proteins can directly interact with each other. Pneumococcal ComGG stabilizes the minor pilin ComGD and ComGF and can interact with and stabilize the major pilin ComGC, thus, deletion of ComGG abolishes competence pilus assembly. We further demonstrate that minor pilins are present in sheared pili fractions and find ComGF to be incorporated along the competence pilus by immunofluorescence and electron microscopy. Finally, mutants of the invariant Glu5 residue (E5), ComGDE5A or ComGEE5A, but not ComGFE5A, were severely impaired in pilus formation and function. Together, our results suggest that ComGG, lacking E5, is essential for competence pilus assembly and function, and plays a central role in connecting the pneumococcal minor pilins to ComGC.

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POPDC proteins and cardiac function

Biochemical Society Transactions ◽

10.1042/bst20190249 ◽

2019 ◽

Vol 47 (5) ◽

pp. 1393-1404 ◽

Cited By ~ 4

Author(s):

Thomas Brand

Keyword(s):

Potential Role ◽

Striated Muscle ◽

Short Review ◽

Effector Proteins ◽

Muscle Disease ◽

Disease Genes ◽

Protein Protein Interaction ◽

Interaction Partners ◽

And Function

Abstract The Popeye domain-containing gene family encodes a novel class of cAMP effector proteins in striated muscle tissue. In this short review, we first introduce the protein family and discuss their structure and function with an emphasis on their role in cyclic AMP signalling. Another focus of this review is the recently discovered role of POPDC genes as striated muscle disease genes, which have been associated with cardiac arrhythmia and muscular dystrophy. The pathological phenotypes observed in patients will be compared with phenotypes present in null and knockin mutations in zebrafish and mouse. A number of protein–protein interaction partners have been discovered and the potential role of POPDC proteins to control the subcellular localization and function of these interacting proteins will be discussed. Finally, we outline several areas, where research is urgently needed.

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Progress in ultrastructural and molecular analysis of the nuclear matrix

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100122940 ◽

1992 ◽

Vol 50 (1) ◽

pp. 508-509

Author(s):

Edward G. Fey

Keyword(s):

Electron Microscopy ◽

Nuclear Matrix ◽

Structure And Function ◽

Matrix Proteins ◽

Rna Transcription ◽

Nuclear Matrix Proteins ◽

The Past ◽

And Function

In the past few years, considerable advances have been made regarding the structure and function of the nuclear matrix. In the first half of this presentation, the field of nuclear matrix research will be summarized. Emphasis will be placed on those studies where molecular interactions are demonstrated in situ utilizing high resolution light and/or electron microscopy. Studies demonstrating the role of the nuclear matrix in DNA synthesis and replication, RNA transcription and processing, and the binding of matrix attachment regions to specific nuclear matrix proteins will be summarized.

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What microscopic studies of confronting cisternae and annulate lamellae reveal about their similarities and differences

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100141007 ◽

1995 ◽

Vol 53 ◽

pp. 926-927

Author(s):

John R. Palisano ◽

Karen S. Renzaglia

Keyword(s):

Electron Microscopy ◽

Tumor Cells ◽

Mitotic Cell ◽

Annulate Lamellae ◽

Proliferative Stage ◽

Dividing Cells ◽

Microscopic Studies ◽

Similarities And Differences ◽

And Function

Knowledge of the origin and function of confronting cisternae (CC) and annulate lamellae (AL) has been limited because they are so infrequently observed. CC were first described by Porter in 1955 and have since been observed in a variety of rapidly proliferating tumor cells and selected fetal tissues. AL were first reported in 1952 by McCullough in sea urchin eggs. Although AL have since been observed in a variety of cells, they have been predominately found in oocytes, spermatocytes, and tumor cells. A microscopic study was initiated to gain a better understanding of the origin and role of these two membranous organelles that are frequently found in rapidly dividing cells that lose the ability to express these organelles once their rapid proliferative stage ceases. Because it has proven difficult to interpret the flow of membrane in the mitotic cell by electron microscopy alone, data obtained by electron microscopy was correlated with fluorescence microscopy wherever possible.

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The role of the integral membrane nucleoporins Ndc1p and Pom152p in nuclear pore complex assembly and function

The Journal of Cell Biology ◽

10.1083/jcb.200506199 ◽

2006 ◽

Vol 173 (3) ◽

pp. 361-371 ◽

Cited By ~ 65

Author(s):

Alexis S. Madrid ◽

Joel Mancuso ◽

W. Zacheus Cande ◽

Karsten Weis

Keyword(s):

Electron Microscopy ◽

Saccharomyces Cerevisiae ◽

Nuclear Envelope ◽

Lipid Bilayers ◽

Nuclear Pore Complex ◽

Transmembrane Proteins ◽

Nuclear Pore ◽

Large Channel ◽

And Function

The nuclear pore complex (NPC) is a large channel that spans the two lipid bilayers of the nuclear envelope and mediates transport events between the cytoplasm and the nucleus. Only a few NPC components are transmembrane proteins, and the role of these proteins in NPC function and assembly remains poorly understood. We investigate the function of the three integral membrane nucleoporins, which are Ndc1p, Pom152p, and Pom34p, in NPC assembly and transport in Saccharomyces cerevisiae. We find that Ndc1p is important for the correct localization of nuclear transport cargoes and of components of the NPC. However, the role of Ndc1p in NPC assembly is partially redundant with Pom152p, as cells lacking both of these proteins show enhanced NPC disruption. Electron microscopy studies reveal that the absence of Ndc1p and Pom152p results in aberrant pores that have enlarged diameters and lack proteinaceous material, leading to an increased diffusion between the cytoplasm and the nucleus.

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Effects of Vinblastine on the Structure and Function of the Rat Exorbital Lacrimal Gland

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100091810 ◽

1976 ◽

Vol 34 ◽

pp. 366-367

Author(s):

Robert B. Kelly

Keyword(s):

Electron Microscopy ◽

Lacrimal Gland ◽

Untreated Control ◽

Acinar Cells ◽

Structure And Function ◽

Cytoplasmic Microtubules ◽

And Function

Antimicrotubular agents such as vinblastine and colchicine have been used to assess the role of cytoplasmic microtubules in secretory processes (for review, see 1). The purpose of this study was to determine the effects of vinblastine on the structure and function of resting and pilocarpine- stimulated acinar cells of the rat exorbital lacrimal gland.Rats were divided into four groups: (a) untreated control; (b) vinblastine (4 mg/kg) treatment for 1 to 24 hours; (c) pilocarpine (20 mg/kg) treatment for 1 hour; and (d) vinblastine treatment for 1 hour, followed by pilocarpine treatment for 1 hour. Both drugs were administered via single intraperitoneal injections. The glands were fixed by perfusion and processed for electron microscopy.

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Role of different domains in the self-association of rat nucleoporin p62

Journal of Cell Science ◽

10.1242/jcs.107.2.631 ◽

1994 ◽

Vol 107 (2) ◽

pp. 631-638

Author(s):

F. Buss ◽

H. Kent ◽

M. Stewart ◽

S.M. Bailer ◽

J.A. Hanover

Keyword(s):

Electron Microscopy ◽

Association Studies ◽

Coiled Coil ◽

Small Region ◽

C Terminus ◽

Linear Chains ◽

Beta Structure ◽

Self Association ◽

And Function

We have expressed rat nucleoporin p62 cDNA in Escherichia coli to obtain material for structural and self-association studies. Electron microscopy and circular dichroism spectroscopy are consistent with a rod-shaped molecule with an alpha-helical coiled-coil domain at its C terminus and a cross-beta structure at its N terminus, separated by a threonine-rich linker, which has a less-defined secondary structure. Electron microscopy and the solubility properties of fragments produced using thrombin and CNBr digestion indicate that p62 molecules associate to form linear chains and that a small region near the C terminus is an important determinant of assembly. This association may have important consequences for pore structure and function; for example, one way p62 could associate would be to form rings in nuclear pores that could function like barrel hoops.

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Faculty Opinions recommendation of Type IV pilus biogenesis in Neisseria meningitidis: PilW is involved in a step occurring after pilus assembly, essential for fibre stability and function.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1023730.279680 ◽

2005 ◽

Author(s):

Tracy Raivio

Keyword(s):

Neisseria Meningitidis ◽

Type Iv Pilus ◽

Type Iv ◽

Pilus Biogenesis ◽

And Function ◽

Pilus Assembly

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Choline-Binding Protein D (CbpD) in Streptococcus pneumoniae Is Essential for Competence-Induced Cell Lysis

Journal of Bacteriology ◽

10.1128/jb.187.13.4338-4345.2005 ◽

2005 ◽

Vol 187 (13) ◽

pp. 4338-4345 ◽

Cited By ~ 87

Author(s):

Louise Kausmally ◽

Ola Johnsborg ◽

Merete Lunde ◽

Eivind Knutsen ◽

Leiv Sigve Håvarstein

Keyword(s):

Streptococcus Pneumoniae ◽

Genetic Transformation ◽

Binding Protein ◽

Bacterial Species ◽

Ectopic Expression ◽

Cell Lysis ◽

Extracellular Dna ◽

Naked Dna ◽

Dna Release ◽

Natural Genetic Transformation

ABSTRACT Streptococcus pneumoniae is an important human pathogen that is able to take up naked DNA from the environment by a quorum-sensing-regulated process called natural genetic transformation. This property enables members of this bacterial species to efficiently acquire new properties that may increase their ability to survive and multiply in the human host. We have previously reported that induction of the competent state in a liquid culture of Streptococcus pneumoniae triggers lysis of a subfraction of the bacterial population resulting in release of DNA. We have also proposed that such competence-induced DNA release is an integral part of natural genetic transformation that has evolved to increase the efficiency of gene transfer between pneumococci. In the present work, we have further elucidated the mechanism behind competence-induced cell lysis by identifying a putative murein hydrolase, choline-binding protein D (CbpD), as a key component of this process. By using real-time PCR to estimate the amount of extracellular DNA in competent relative to noncompetent cultures, we were able to show that competence-induced cell lysis and DNA release are strongly attenuated in a cbpD mutant. Ectopic expression of CbpD in the presence or absence of other competence proteins revealed that CbpD is essentially unable to cause cell lysis on its own but depends on at least one additional protein expressed during competence.

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