[Extremely low birth weight (less than 1000 gram) and early postnatal weight gain in preterm infants]. / Extrémen alacsony születési súlyú (< 1000 g) koraszülöttek korai postnatalis súlygyarapodása.

Improving survival of extremely low birthweight (< 1000 g) preterm infants opens the practical issues of their postnatal nutrition and growth. The authors studied nutrition and weight gain in 16 extremely low birthweight preterm infants (birthweight: 890 +/- 22 g, gestational age: 28.0 +/- 0.2 week, mean +/- SEM) during the first 12 weeks of life. Milk of the mother, or fortified pooled human milk or preterm infant formula was fed. The preterm infants approximated their birthweight by the end of the 3rd week of life (21st day: 866 +/- 29 g). Body weight expressed as per cent of birthweight was 109 +/- 2% at the end of the 4th, 176 +/- 7% at the end of the 8th and 275 +/- 6% at the end of the 12th week of life. Weight gain during the 1st to 8th postnatal weeks was compared to the mean in utero weight gain of foetuses with identical gestational age, gender and weight percentile position. Cumulative weight gain of preterm infants during the first 8 weeks of life was significantly lower than that of the theoretical controls (76 +/- 7% versus 136 +/- 2%, per cent of the initial value, preterm versus control, p < 0.0001). Additional weight gain of preterm infants was lower than that of the controls on the 1st to 5th weeks of life (g/kg/day, 1st week: -14.4 +/- 1.6 versus 16.7 +/- 0.5, p < 0.0001; 5th week: 13.3 +/- 1.2 versus 16.4 +/- 0.3, p < 0.05), there were no differences between the two groups on the 6th and 7th weeks, whereas preterm infants gained significantly more weight on the 8th week of life than the theoretical control value (18.2 +/- 0.9 versus 14.0 +/- 0.2, p < 0.001). These data indicate that the first weeks of life represent an especially important period for the improvement of the nutrition of extremely low birthweight preterm infants.

Novel phosphotransferase systems revealed by bacterial genome analysis: the complete repertoire of pts genes in Pseudomonas aeruginosa.

We herein describe all genes encoding constituents of the phosphoenolpyruvate:sugar phosphotransferase system (PTS) in the 6Mbp genome of the opportunistic human pathogen, Pseudomonas aeruginosa. Only four gene clusters were found to encode identifiable PTS homologues. These genes clusters encode novel multidomain proteins, two complete sugar-specific PTS phosphoryl transfer chains for the metabolism of fructose and N-acetylglucosamine, and a complex regulatory system that may function to coordinate carbon and nitrogen metabolism. No previously characterized organism has been shown to exhibit such a novel and restricted complement of PTS proteins.

6-phospho-alpha-D-glucosidase from Fusobacterium mortiferum: cloning, expression, and assignment to family 4 of the glycosylhydrolases.

The Fusobacterium mortiferum malH gene, encoding 6-phospho-alpha-glucosidase (maltose 6-phosphate hydrolase; EC 3.2.1.122), has been isolated, characterized, and expressed in Escherichia coli. The relative molecular weight of the polypeptide encoded by malH (441 residues; Mr of 49,718) was in agreement with the estimated value (approximately 49,000) obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis for the enzyme purified from F. mortiferum. The N-terminal sequence of the MalH protein obtained by Edman degradation corresponded to the first 32 amino acids deduced from the malH sequence. The enzyme produced by the strain carrying the cloned malH gene cleaved [U-14C]maltose 6-phosphate to glucose 6-phosphate (Glc6P) and glucose. The substrate analogs p-nitrophenyl-alpha-D-glucopyranoside 6-phosphate (pNP alphaGlc6P) and 4-methylumbelliferyl-alpha-D-glucopyranoside 6-phosphate (4MU alphaGlc6P) were hydrolyzed to yield Glc6P and the yellow p-nitrophenolate and fluorescent 4-methylumbelliferyl aglycons, respectively. The 6-phospho-alpha-glucosidase expressed in E. coli (like the enzyme purified from F. mortiferum) required Fe2+, Mn2+, Co2+, or Ni2+ for activity and was inhibited in air. Synthesis of maltose 6-phosphate hydrolase from the cloned malH gene in E. coli was modulated by addition of various sugars to the growth medium. Computer-based analyses of MalH and its homologs revealed that the phospho-alpha-glucosidase from F. mortiferum belongs to the seven-member family 4 of the glycosylhydrolase superfamily. The cloned 2.2-kb Sau3AI DNA fragment from F. mortiferum contained a second partial open reading frame of 83 residues (designated malB) that was located immediately upstream of malH. The high degree of sequence identity of MalB with IIB(Glc)-like proteins of the phosphoenol pyruvate dependent:sugar phosphotransferase system suggests participation of MalB in translocation of maltose and related alpha-glucosides in F. mortiferum.

Characterization of a family of bacterial response regulator aspartyl-phosphate (RAP) phosphatases.

We have characterized a novel family of response regulator aspartyl-phosphate (RAP) phosphatases found exclusively in gram-positive bacteria. The family consists of 15 members, 12 of which are from Bacillus subtilis. The N-terminal domains proved to be more highly conserved than the C-terminal domains, and a signature sequence for the family was derived from the former domains. Phylogenetic analyses revealed clustering patterns showing that all Bacillus proteins are closely related. Most of the Bacillus RAP phosphatase genes are followed by and are translationally coupled to small nonhomologous phosphatase regulator (phr) genes that encode exported peptides with regulatory functions. Most of the paralogous RAP phosphatases of B. subtilis may serve related functions in signal transduction systems. They appear to have arisen by relatively recent gene duplication events that occurred after the divergence of major groups within the gram-positive bacterial kingdom. We suggest that the N-terminal domains of the RAP phosphatases function in catalysis, whereas the C-terminal domains function in regulation.

Novel phosphotransferase-encoding genes revealed by analysis of the Escherichia coli genome: a chimeric gene encoding an Enzyme I homologue that possesses a putative sensory transduction domain.

Two genes (ptsI and ptsA) that encode homologues of the energy coupling Enzyme I of the phosphoenolpyruvate-dependent sugar-transporting phosphotransferase system (PTS) have previously been identified on the Escherichia coli chromosome. We here report the presence of a third E. coli gene, designated ptsP, that encodes an Enzyme I homologue, here designated Enzyme INtr. Enzyme INtr possesses an N-terminal domain homologous to the N-terminal domains of NifA proteins [(127 amino acids (aa)] joined via two tandem flexible linkers to the C-terminal Enzyme I-like domain (578 aa). Structural features of the putative ptsP operon, including transcriptional regulatory signals, are characterized. We suggest that Enzyme INtr functions in transcriptional regulation of nitrogen-related operons together with previously described PTS proteins encoded within the rpoN operon. It may thereby provide a link between carbon and nitrogen assimilatory pathways.

Novel PTS proteins revealed by bacterial genome sequencing: a unique fructose-specific phosphoryl transfer protein with two HPr-like domains in Haemophilus influenzae.

The completely sequenced genome of Haemophilus influenzae has been analysed for proteins of the phosphoenolpyruvate: sugar phosphotransferase system (PTS). We show that within the fructose PTS H. influenzae possesses a novel multi-domain phosphoryl transfer protein, not previously recognized, that includes two fructose-specific HPr domains fused in tandem in a single polypeptide chain.

Novel phosphotransferase system genes revealed by bacterial genome analysis: the complete complement of pts genes in mycoplasma genitalium.

The complete sequence of the Mycoplasma genitalium chromosome has recently been determined. We here report analyses of the genes encoding proteins of the phosphoenolpyruvate:sugar phosphotransferase system, PTS. These genes encode (1) Enzyme I, (2) HPr, (3) a glucose-specific Enzyme IICBA, (4) an inactive glucose-specific Enzyme IIB, lacking the active site cysteyl residue, and (5) a fructose-specific Enzyme IIABC. Some of the unique features of these genes and their enzyme products are as follows. (1) Each of the genes is encoded within a distinct operon. (2) Both Enzyme I and HPr have basic isoelectric points. (3) The glucose-specific Enzyme IIC bears a centrally located, hydrophilic, 200 amino acyl residue insert that lacks sequence similarity with any protein in the current database. (4) The fructose-specific Enzyme II has a domain order (IIABC), different from those of previously characterized fructose permeases, and its IIA domain more closely resembles the IIANtr protein of Escherichia coli than other fructose-specific IIA domains. The potential significance of these novel features is discussed.

Novel phosphotransferase system genes revealed by bacterial genome analysis--a gene cluster encoding a unique Enzyme I and the proteins of a fructose-like permease system.

Previous publications have demonstrated the presence of a cryptic gene encoding a novel Enzyme I of the phosphoenolpyruvate:sugar phosphotransferase system (PTS). Recent Escherichia coli genome sequencing revealed a gene (ptsA) encoding a new Enzyme I homologue in the 89.1-89.3 centisome region. We have analysed this region, and here describe and characterize open reading frames (ORFs) encoding (1) a fused PTS Enzyme I-IIAFru homologue, (2) a glycerol dehydrogenase, (3) a transaldolase homologue, (4) two PTS IIBFru homologues, (5) a PTS IICFru homologue, and (6) homologues of pyruvate formate-lyase and its activating enzyme. Binary comparison scores, multiple alignments and phylogenetic trees establish the families of proteins to which each of the relevant ORFs belong. Identification of the putative products of this gene cluster leads to the proposal that several of the proteins encoded in this region function in anaerobic carbon metabolism.

Novel proteins of the phosphotransferase system encoded within the rpoN operon of Escherichia coli. Enzyme IIANtr affects growth on organic nitrogen and the conditional lethality of an erats mutant.

Two rpoN-linked delta Tn10-kan insertions suppress the conditionally lethal erats allele. One truncates rpoN while the second disrupts another gene (ptsN) in the rpoN operon and does not affect classical nitrogen regulation. Neither alter expression of era indicating that suppression is post-translational. Plasmid clones of ptsN prevent suppression by either disruption mutation indicating that this gene is important for lethality caused by erats. rpoN and six neighboring genes were sequenced and compared with sequences in the database. Two of these genes encode proteins homologous to Enzyme IIAFru and HPr of the phosphoenolpyruvate:sugar phosphotransferase system. We designate these proteins IIANtr (ptsN) and NPr (npr). Purified IIANtr and NPr exchange phosphate appropriately with Enzyme I, HPr, and Enzyme IIA proteins of the phosphoenolpyruvate: sugar phosphotransferase system. Several sugars and tricarboxylic acid cycle intermediates inhibited growth of the ptsN disruption mutant on medium containing an amino acid or nucleoside base as a combined source of nitrogen, carbon, and energy. This growth inhibition was relieved by supplying the ptsN gene or ammonium salts but was not aleviated by altering levels of exogenously supplied cAMP. These results support our previous proposal of a novel mechanism linking carbon and nitrogen assimilation and relates IIANtr to the unknown process regulated by the essential GTPase Era.

Nucleotide sequence of the region between crr and cysM in Salmonella typhimurium: five novel ORFs including one encoding a putative transcriptional regulator of the phosphotransferase system.

A 4471 bp region between crr and cysM on the Salmonella typhimurium chromosome (49.5 min) has been sequenced. Five ORFs were found within this region, one of which is likely to be the putative regulatory gene, ptsJ, that corresponds in map position to a gene which when mutated allows expression of a cryptic Enzyme I of the phosphotransferase system. The deduced amino acid sequence of the encoded protein is similar to those of several open reading frames (ORFs) including ORFT2 of Rhodobacter spheroides with which it is 28% identical throughout most of its length (comparison score of 21 S.D.). PtsJ exhibits a putative, N-terminal, helix-turn-helix, DNA binding domain that is similar in sequence to those in members of the GntR family of transcriptional regulators. Analyses of the sequences of the ORFs encoded within this region are presented.

Evolutionary relationships between sugar kinases and transcriptional repressors in bacteria.

We have characterized a new family of proteins (the ROK family) which includes six transcriptional repressors for sugar catabolic operons, three sugar kinases, and three unidentified open reading frames. Analysis of the aligned sequences and phylogenetic tree construction allow predictions regarding the functional nature of conserved domains and residues within these proteins as well as the pathway of evolutionary divergence that gave rise to the family.

A functional superfamily of sodium/solute symporters.

Eleven families of sodium/solute symporters are defined based on their degrees of sequence similarities, and the protein members of these families are characterized in terms of their solute and cation specificities, their sizes, their topological features, their evolutionary relationships, and their relative degrees and regions of sequence conservation. In some cases, particularly where site-specific mutagenesis analyses have provided functional information about specific proteins, multiple alignments of members of the relevant families are presented, and the degrees of conservation of the mutated residues are evaluated. Signature sequences for several of the eleven families are presented to facilitate identification of new members of these families as they become sequenced. Phylogenetic tree construction reveals the evolutionary relationships between members of each family. One of these families is shown to belong to the previously defined major facilitator superfamily. The other ten families do not show sufficient sequence similarity with each other or with other identified transport protein families to establish homology between them. This study serves to clarify structural, functional and evolutionary relationships among eleven distinct families of functionally related transport proteins.

A novel zinc-binding motif found in two ubiquitous deaminase families.

Two families of deaminases, one specific for cytidine, the other for deoxycytidylate, are shown to possess a novel zinc-binding motif, here designated ZBS. We have (1) identified the protein members of these 2 families, (2) carried out sequence analyses that allow specification of this zinc-binding motif, and (3) determined signature sequences that will allow identification of additional members of these families as their sequences become available.

Sequence of the fruB gene of Escherichia coli encoding the diphosphoryl transfer protein (DTP) of the phosphoenolpyruvate: sugar phosphotransferase system.

The Escherichia coli genome sequencing project in the 47 to 48 centisome region has resulted in the sequencing of the complete fructose operon (fruBKA). Due to a single base insertion, the presence of the fruB gene went unnoticed. The revised nucleotide sequence of the fruB gene, the deduced amino acid sequence of its protein product, the diphosphoryl transfer protein of the phosphoenolpyruvate: sugar phosphotransferase system, and putative transcriptional regulatory signals of the fru operon of E. coli are here presented and compared with that from Salmonella typhimurium.