Papers of the month

2013

• September 2013
  • Biofilms of B. subtilis consist of cells in a matrix made up of extracellular polysaccharides, the amyloid-like TasA protein, and the hydrophobic protein BslA. Now, Hobley et al. from the lab of Nicola Stanley-Wall determined the structure of BslA and found that the protein has an extremely hydrophobic cap domain that acts like a raincoat for the biofilm. The authors suggest that BslA is a bacterial hydrophobin.
  • Relevant SubtiWiki pages: Nicola Stanley-Wall, biofilm formation, BslA

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• August 2013
  • In cells, the concentration of ribonucleotides by far exceeds that of deoxyribonucleotides. This poses problems since the DNA polymerase incorporates one rNTP every 2.3 kb during chromosome replication. Now, Yao et al. investigated how these misincorporations are repaired. They demonstrate that this repair is initiated by RNase HII that nicks DNA at single rNMP residues to initiate replacement with dNMPs.
  • Relevant SubtiWiki pages: DNA replication, DNA repair, rnhB, rnhC, mutS, mutL

• July 2013
  • Ca²⁺ efflux by Ca²⁺ cation antiporter (CaCA) proteins is important for maintenance of Ca²⁺ homeostasis across the cell membrane. Now, Wu et al. determined the structure of the B. subtilis Ca²⁺/H⁺ antiporter protein ChaA. By structural and mutational analyses, they establish structural bases for mechanisms of Ca²⁺/H⁺ exchange and its pH regulation. Moreover, this work also sheds light on the evolutionary adaptation to different energy modes in the CaCA protein family.
  • Relevant SubtiWiki pages: ChaA, membrane proteins, metal ion homeostasis (K, Na, Ca, Mg)

• June 2013
  • DNA transfer across membranes is important in many fundamental processes. However, the molecular mechanisms behind this transport are only poorly understood. Now, Fiche et al. analysed the assembly and molecular architecture of the SpoIIIE DNA translocation complex. This study reveals that in contrast to a previous model, DNA transfer occurs through an aqueous DNA-conducting pore that could be structurally maintained by the divisional machinery, with SpoIIIE acting as a checkpoint preventing membrane fusion until completion of chromosome segregation.
  • Relevant SubtiWiki pages: sporulation, SpoIIIE, DNA condensation/ segregation

• May 2013
  • Paul et al. demonstrate that the orientation of the genes on the chromosome has a significant impact on their evolution: Gene encoded on the lagging strand evolve faster than those on the leading strand. This faster evolution is caused by collisions between the DNA replication and transcription machineries that result in DNA damage and subsequent fixation of errors as mutations. Importantly, essential genes are strongly underrepresented on the lagging strand thus providing a "built-in" protection of the encoded important proteins against possible deleterious mutations.
  • Relevant SubtiWiki pages: transcription, DNA replication, essential genes

• April 2013
  • Usually, cell wall synthesis is regarded as being essential for B. subtilis. Now, Mercier et al. from the lab of Jeff Errington show that excess biosynthesis of membranes is sufficient to drive the formation of cell wall-less L-forms in B. subtilis. Interestingly, this cell form is even independent of the essential cell division protein FtsZ.
  • Relevant SubtiWiki pages: Jeff Errington, biosynthesis of lipids, cell wall synthesis, cell division, FtsZ

• March 2013
  • The mechanism of membrane fission in bacteria has been a long-standing enigma. Now, Doan et al. from the lab of David Rudner demonstrate how the FisB protein (previously YunB) mediates membrane fission during sporulation This activity of FisB is based on its ability to bind to lipids, specifically to cardiolipin.
  • Relevant SubtiWiki pages: David Rudner, FisB, sporulation

• See also:

• February 2013
  • For many essential genes of B. subtilis, it is not clear why they are essential in B. subtilis but not in closely related species. Strikingly, this is the case for RNases such as RNases III and Y. Now, Durand et al. from the lab of Ciaran Condon have identified the reason for the essentiality of RNase III: This enzyme is required to degrade phage encoded toxin mRNA molecules thus protecting the cell from lysis caused by the encoded toxins. Indeed, RNase III is dispensable in a strain lacking the Skin element and the SPß prophage that harbor the corresponding toxin genes.
  • Relevant SubtiWiki pages: Ciaran Condon, RNase III, essential genes, yonT, txpA, toxins, antitoxins and immunity against toxins

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• January 2013
  • Castaing et al. from the lab of Kumaran Ramamurthi show how ATP hydrolysis drives the self-association of SpoIVA into nucleotide-free filaments which then serve as a platform for the assembly of the spore coat starting with SpoVM. Together with the december's paper of the month these works demonstrate how ATP hydrolysis may contribute to different processes within a protein such as global conformational changes and self-assembly.
  • Relevant SubtiWiki pages: Kumaran Ramamurthi, SpoIVA, sporulation

2012

• December 2012
  • Kim et al. show how the ATP hydrolysis controls the global conformation of the SecA translocase and drives protein secretion. The intricate network of structural interactions, which couple local electrostatic changes during ATP hydrolysis to global conformational and dynamic changes in SecA, form the foundation of the allosteric mechanochemistry that efficiently harnesses the chemical energy stored in ATP to drive complex mechanical processes.
  • Relevant SubtiWiki pages: SecA, protein secretion

• November 2012
  • Watson and Fedor identify the first ATP-responsive riboswitch. This riboswitch controls the expression of the ydaO gene and the ktrA-ktrB operon. Gene expression is decreased upon binding of ATP to the riboswitch. In consequence, the target genes are induced if the energy charge of the cell is low.
  • Relevant SubtiWiki pages: ydaO, ydaO riboswitch, riboswitch, ktrA-ktrB

• October 2012
  • Plata et al. from the labs of Dennis Vitkup and Uwe Sauer use a probabilistic approach to annotate genome-scale metabolic networks that integrates sequence homology and context-based correlations to functionally annotate so far unknown enzymes.
  • Relevant SubtiWiki pages: ykgB, spsI, spsJ, Uwe Sauer, Dennis Vitkup, metabolism

• September 2012
  • Chiba and Ito studied how the translation of YidC2, a membrane protein biogenesis factor, is controlled by SpoIIIJ availability via ribosome stalling of the mifM mRNA.
  • Relevant SubtiWiki pages: Koreaki Ito, translation, YidC2, SpoIIIJ, mifM

• August 2012
  • Houry et al. from the lab of Romain Briandet showed how motile Bacillus thuringiensis bacteria can penetrate a Staphylococcus aureus biofilm and eventually kill the biofilm bacteria with their antibacterial compounds.
  • Relevant SubtiWiki pages: Romain Briandet, Stephane Aymerich, biofilm formation, biosynthesis of antibacterial compounds

• July 2012
  • Dago et al. from the lab of Hendrik Szurmant studied the interactions between histidine kinase domains of two-component systems that result in autophosphorylation.
  • Relevant SubtiWiki pages: Hendrik Szurmant, Jim Hoch, two-component systems, KinA, KinD, protein-protein interactions

• June 2012
  • Kolodkin-Gal et al. from the labs of Roberto Kolter and Richard Losick demonstrate that D-amino acids produced by RacX and YlmE and norspermidine produced by GabT and YaaO act together in preventing biofilm formation and triggering biofilm disassembly.
  • Relevant SubtiWiki pages: Roberto Kolter, Richard Losick, biofilm formation, RacX, YlmE, GabT, YaaO

• May 2012
  • Elsholz et al. from the lab of Ulf Gerth demonstrate that protein phosphorylation on arginine residues is of great importance for B. subtilis. In addition to the previously identified target CtsR, 86 proteins are shown to be phosphorylated on arginine. The protein arginine kinase and phosphatase, McsB and YwlE, respectively, may thus have an important regulatory role in B. subtilis.
  • Relevant SubtiWiki pages: Ulf Gerth, Kürsad Turgay, Ulrike Mäder, Dörte Becher, Michael Hecker, phosphoproteins, protein kinases and phosphatases, McsB, YwlE

• April 2012
  • Meisner et al. and Levdikov et al. from the labs of Charles Moran and Tony Wilkinson, respectively, have reported the structure of the complex between SpoIIQ and SpoIIIAH. These two proteins interact through two membranes to connect the forespore and the mother cell during sporulation. The structure of the complex suggests that it is the extracellular component of a gap junction-like intercellular channel for the traffic of proteins between the two compartments.
  • Relevant SubtiWiki pages: Charles Moran, Tony Wilkinson, sporulation, SpoIIQ, SpoIIIAH

• March 2012
  • Buescher et al. and Nicolas et al. from the BaSysBio consortium diected by Philippe Noirot studied the dynamic metabolic and transcriptional responses of B. subtilis to changes of the growth conditions. One of the major issues is the adaptation of the cells upon a nutrient switch from glucose to malate and vice versa. Importantly, the study by Nicholas et al. provides an analysis of gene expression at 104 different conditions as revealed by tiling arrays.
  • Relevant SubtiWiki pages: Philippe Noirot, Michael Hecker, Uwe Völker, Philippe Bessières, Uwe Sauer, Stephane Aymerich, Tony Wilkinson, metabolism, transcription, CcpA, Sigma factors, sRNAs, Rho

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• February 2012
  • Levine et al. from the lab of Michael Elowitz show how B. subtilis cells can defer sporulation for multiple cell cycles in response to sudden environmental stress. This deferral is controlled by a pulsed positive feedback loop in which phosphorelay kinase expression is activated by pulses of Spo0A phosphorylation.
  • Relevant SubtiWiki pages: Michael Elowitz, Jonathan Dworkin, phosphorelay, sporulation, Spo0A

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• January 2012
  • Segev et al. from the lab of Sigal Ben-Yehuda demonstrate that ribosomal RNAs are degraded in aging spores by RNase Y. Moreover, the authors show that individual mRNAs experience degradation or accumulation in spores. The study suggests that the kinetics of spore germination depends on the conditions that a spore had experienced before.
  • Relevant SubtiWiki pages: Sigal Ben-Yehuda, RNase Y, germination, RNases

2011

• December 2011
  • Bange et al. from the lab of Irmgard Sinning show how the FlhG protein activates the SRP-GTPase FlhF. The study sheds light on the evolutionary transition from RNA- to protein-driven activation in SRP-GTPases.
  • Relevant SubtiWiki pages: Irmgard Sinning, FlhF, FlhG, signal recognition particle, motility and chemotaxis

• November 2011
  • Locke et al. show how the SigB-dependent general stress response is controlled by signals using stochastic pulse frequency modulation through a compact regulatory architecture.
  • Relevant SubtiWiki pages: Michael Elowitz, SigB, General stress response

• October 2011
  • Richards et al. identify the nudix hydrolase RppH as the pyrophosphohydrolase that triggers 5'-exonucleolytic degradation of mRNA by RNase J1 in B. subtilis.
  • Relevant SubtiWiki pages: David Bechhofer, Ciaran Condon, RNA processing and degradation, nudix hydrolase, RppH, RNase J1

• September 2011
  • A series of papers deals with RNA processing and degradation in B. subtilis. Three papers establish that RNase Y is the functional equivalent of RNase E from E. coli. Moreover, the role of RNase J1 in endonucleolytic cleavage of the trp leader mRNA is demonstrated.
  • Relevant SubtiWiki pages: David Bechhofer, Rick Lewis, Ulrike Mäder, Harald Putzer, Jörg Stülke, RNases, RNA degradosome, RNase Y, RNase Y targets, RNase J1

• August 2011
  • Chi et al. demonstrate that S-bacillithiolation of the repressor OhrR and of four enzymes of the methionine biosynthesis pathway protects the B. subtilis cell against hypochlorite stress.
  • Relevant SubtiWiki pages: Haike Antelmann, Dörte Becher, Ulrike Mäder, resistance against oxidative and electrophile stress, Spx regulon, CtsR regulon, PerR regulon, OhrR, MetE, YxjG, PpaC, SerA, YphP

• July 2011
  • Domínguez-Escobar et al. from Rut Carballido-Lopez' lab and Garner et al. report that movement of actin-like filaments is driven by the peptidoglycan elongation machinery. Both papers suggest that the MreB-like filaments serve to restrict the mobility of the peptidoglycan synthesizing machinery
    
  • Relevant SubtiWiki pages: Rut Carballido-Lopez, David Rudner, MreB, MreBH, Mbl, MreC, MreD, PbpA, RodA, RodZ, penicillin-binding proteins, cell shape, cell wall synthesis, cell wall biosynthetic complex

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• June 2011
  • Oppenheimer-Shaanan et al. from Sigal Ben-Yehuda's lab report that cyclic di-AMP acts as a secondary messenger that couples DNA integrity with progression of sporulation
    
  • Relevant SubtiWiki pages: Sigal Ben-Yehuda, DisA, GdpP, metabolism of signalling nucleotides, cell division

• May 2011
  • Miles et al. identified the enzyme for the key final step in the biosynthesis of queuosine, a hypermodified base found in the wobble positions of tRNA Asp, Asn, His, and Tyr from bacteria to man
    
  • Relevant SubtiWiki pages: QueG, translation