RpoS protein

Examples of RpoS protein in the following topics:

• Regulation of Sigma Factor Translation

  • The most commonly studied sigma factors are often referred to as a RpoS proteins as the rpoS genes encode for sigma proteins of various sizes.
  • Using RpoS proteins as the focus, the RpoS expression and transcription is regulated at the translational level.
  • Small noncoding RNAs are able to sense environmental changes and stresses resulting in increased expression of RpoS protein.
  • The resultant increase of RpoS protein is based on the cellular environment and its needs.
  • These RNAs can induce activation of rpoS translation.

• Small Regulatory RNAs

  • The mechanisms by which small regulatory RNAs function include binding to protein targets, protein modification, binding to mRNA targets, and regulating gene expression .
  • Antisense RNAs are used to bind to complementary mRNAs and inhibit protein translation.
  • RPoS genes specifically encode for sigma factors which function as regulators of transcription and stress responses.
  • Small RNAs have been shown to regulate RPoS translation and those identified thus far include: DsrA, RprA, and OxyS.
  • These RNAs can either activate or inhibit RPoS translation.

• Verrucomicrobia

  • Support for this superphylum has been found by examining the RNA polymerase protein RpoB.
  • rpoB is the gene that encodes the β subunit of bacterial RNA polymerase.
  • This protein has a unique 3 amino acid insert in all sequenced Chlamydiae, Lentisphaerae and Verrucomicrobia species.
  • This protein is absent in the Poribacteria.
  • On the single circular chromosome, 2473 predicted proteins were found, 731 of which had no detectable homologs.

• The Complement System

  • Cells of the liver and macrophages synthesize complement proteins continuously.
  • Binding of complement proteins occurs in a specific and highly-regulated sequence, with each successive protein being activated by cleavage and/or structural changes induced upon binding of the preceding protein(s).
  • After the first few complement proteins bind, a cascade of sequential binding events follows in which the pathogen rapidly becomes coated in complement proteins.
  • Complement proteins perform several functions.
  • Pathogens lacking these regulatory proteins are lysed.

• Purifying Proteins by Affinity Tag

  • Protein tags are peptide sequences genetically grafted onto a recombinant protein.
  • Protein tags are peptide sequences genetically grafted onto a recombinant protein.
  • These include chitin binding protein (CBP), maltose binding protein (MBP), and glutathione-S-transferase (GST).
  • BCCP (Biotin Carboxyl Carrier Protein), a protein domain recognized by streptavidin
  • Green fluorescent protein-tag, a protein which is spontaneously fluorescent and can be bound by nanobodies

• Genomics and Proteomics

  • Proteomics is a relatively-recent field; the term was coined in 1994 while the science itself had its origins in electrophoresis techniques of the 1970's and 1980's.
  • Studying proteins generates insight into how they affect cell processes.
  • Certain proteins in the cancerous cell may not be present in the healthy cell, making these unique proteins good targets for anti-cancer drugs.
  • A proteome is the entire set of proteins produced by a cell type.
  • There are also protein-protein interactions, which complicate the study of proteomes.

• Regulator Molecules of the Cell Cycle

  • Phosphorylation activates the protein by changing its shape.
  • Retinoblastoma proteins are a group of tumor-suppressor proteins common in many cells.
  • As a cell is exposed to more stress, higher levels of p53 and p21 accumulate, making it less likely that the cell will move into the S phase.
  • When Rb is bound to E2F, production of proteins necessary for the G1/S transition is blocked.
  • The concentrations of cyclin proteins change throughout the cell cycle.

• Fluid Mosaic Model

  • The fluid mosaic model was first proposed by S.J.
  • For example, myelin contains 18% protein and 76% lipid.
  • Proteins make up the second major component of plasma membranes.
  • Some complex proteins are composed of up to 12 segments of a single protein, which are extensively folded and embedded in the membrane.
  • This arrangement of regions of the protein tends to orient the protein alongside the phospholipids, with the hydrophobic region of the protein adjacent to the tails of the phospholipids and the hydrophilic region or regions of the protein protruding from the membrane and in contact with the cytosol or extracellular fluid.

• Ribosomes

  • The purpose of the ribosome is to translate messenger RNA (mRNA) into proteins with the aid of tRNA.
  • Ribosomes are tiny spherical organelles that make proteins by joining amino acids together.
  • Proteins synthesized in each of these locations serve a different role in the cell.
  • All prokaryotes have 70S (where S=Svedberg units) ribosomes while eukaryotes contain larger 80S ribosomes in their cytosol.
  • The ribosome assembles amino acids into a protein.

• Group Translocation

  • Proteins may be incorporated into the plasma membrane.
  • In addition, bacteria may target proteins into or across the outer membrane.
  • A specialized enzyme, sortase, cleaves the target protein at a characteristic recognition site near the protein C-terminus, such as an LPXTG motif (where X can be any amino acid), then transfers the protein onto the cell wall.
  • The PGF-CTERM/archaeosortase A system in archaea is related to S-layer production.
  • A fifth Tat protein TatE that is homologous to the TatA protein is present at a much lower level in the cell than TatA.