A cationic lumen in the Wzx flippase mediates anionic O-antigen subunit translocation in Pseudomonas aeruginosa PAO1.

Heteropolymeric B-band O-antigen (O-Ag) biosynthesis in Pseudomonas aeruginosa PAO1 follows the Wzy-dependent pathway, beginning with translocation of undecaprenyl pyrophosphate-linked anionic O-Ag subunits (O units) from the inner to the outer leaflets of the inner membrane (IM). This translocation is mediated by the integral IM flippase Wzx. Through experimentally based and unbiased topological mapping, our group previously observed that Wzx possesses many charged and aromatic amino acid residues within its 12 transmembrane segments (TMS).

ProQ is an RNA chaperone that controls ProP levels in Escherichia coli.

Transporter ProP mediates osmolyte accumulation in Escherichia coli cells exposed to high osmolality media. The cytoplasmic ProQ protein amplifies ProP activity by an unknown mechanism. The N- and C-terminal domains of ProQ are predicted to be structurally similar to known RNA chaperone proteins FinO and Hfq from E.

Transmembrane helix I and periplasmic loop 1 of Escherichia coli ProP are involved in osmosensing and osmoprotectant transport.

Osmoregulatory transporters stimulate bacterial growth by mediating osmoprotectant uptake in response to increasing osmotic pressure. The ProP protein of Escherichia coli transports proline and other osmoprotectants. Like LacY, ProP is a member of the major facilitator superfamily and a H(+)-solute symporter.

Structural modeling identified the tRNA-binding domain of Utp8p, an essential nucleolar component of the nuclear tRNA export machinery of Saccharomyces cerevisiae.

Utp8p is an essential 80 kDa intranuclear tRNA chaperone that transports tRNAs from the nucleolus to the nuclear tRNA export receptors in Saccharomyces cerevisiae. To help understand the mechanism of Utp8p function, predictive tools were used to derive a partial model of the tertiary structure of Utp8p. Secondary structure prediction, supported by circular dichroism measurements, indicated that Utp8p is divided into 2 domains: the N-terminal beta sheet and the C-terminal alpha helical domain.

Periplasmic loops of osmosensory transporter ProP in Escherichia coli are sensitive to osmolality.

ProP is an osmosensory transporter. The activities of ProP and ProP*, a cysteine-less, His(6)-tagged ProP variant, increase with osmotic pressure in cells and proteoliposomes. In proteoliposomes, ProP activity is osmolality-dependent only if the magnitude of the membrane potential (DeltaPsi) exceeds 100 mV.

Core residue replacements cause coiled-coil orientation switching in vitro and in vivo: structure-function correlations for osmosensory transporter ProP.

Protein ProP acts as an osmosensory transporter in diverse bacteria. C-Terminal residues 468-497 of Escherichia coli ProP (ProPEc) form a four-heptad homodimeric alpha-helical coiled coil. Arg 488, at a core heptad a position, causes it to assume an antiparallel orientation.

The structure and function of Saccharomyces cerevisiae proteinase A.

Saccharomyces cerevisiae proteinase A (saccharopepsin; EC 3.4.23.

Structure and function of transmembrane segment XII in osmosensor and osmoprotectant transporter ProP of Escherichia coli.

Escherichia coli transporter ProP acts as both an osmosensor and an osmoregulator. As medium osmolality rises, ProP is activated and mediates H+-coupled uptake of osmolytes like proline. A homology model of ProP with 12-transmembrane (TM) helices and cytoplasmic termini was created, and the protein's topology was substantiated experimentally.

Evidence that WbpD is an N-acetyltransferase belonging to the hexapeptide acyltransferase superfamily and an important protein for O-antigen biosynthesis in Pseudomonas aeruginosa PAO1.

Di-N-acetylated uronic acid residues are unique sugar moieties observed in the lipopolysaccharides (LPS) of respiratory pathogens including several serotypes of Pseudomonas aeruginosa and several species of Bordetella. WbpD of P. aeruginosa PAO1 (serotype O5) is a putative 3-N-acetyltransferase that has been implicated in the biosynthesis of UDP-2,3-diacetamido-2,3-dideoxy-d-mannuronic acid [UDP-d-Man(2NAc3NAc)A], a precursor for the d-Man(2NAc3NAc)A residues in the B-band O antigen of this bacterium.

A structural model for the osmosensor, transporter, and osmoregulator ProP of Escherichia coli.

Transporter ProP of Escherichia coli, a member of the major facilitator superfamily (MFS), acts as an osmosensor and an osmoregulator in cells and after purification and reconstitution in proteoliposomes. H(+)-osmoprotectant symport via ProP is activated when medium osmolality is elevated with membrane impermeant osmolytes. The three-dimensional structure of ProP was modeled with the crystal structure of MFS member GlpT as a template.

Overexpression, purification, and characterization of ProQ, a posttranslational regulator for osmoregulatory transporter ProP of Escherichia coli.

ProP is an osmosensor and osmoregulatory transporter in Escherichia coli. Osmotic activation of ProP is attenuated 5-fold in the absence of soluble protein ProQ, but proQ lesions do not influence proP transcription or ProP levels. The mechanism by which ProQ amplifies ProP activity is unknown.

The Pseudomonas aeruginosa initiation factor IF-2 is responsible for formylation-independent protein initiation in P. aeruginosa.

Formylation of the initiator methionyl-tRNA (Met-tRNAfMet) was generally thought to be essential for initiation of protein synthesis in all eubacteria based on studies conducted primarily in Escherichia coli. However, this view of eubacterial protein initiation has changed because some bacteria have been demonstrated to have the capacity to initiate protein synthesis with the unformylated Met-tRNAfMet. Here we show that the Pseudomonas aeruginosa initiation factor IF-2 is required for formylation-independent protein initiation in P.