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R T Sauer

Publications and source records attributed to R T Sauer.

179 records · Page 10Linked to original sources
PubMed1982

Cleavage of the lambda and P22 repressors by recA protein.

The site of recA cleavage of the phage lambda and P22 repressors has been determined. Each repressor is cut once by the recA enzyme, lambda repressor between residues 111 and 112, and P22 repressor between residues 94 and 95. recA cleavage occurs at identical alanyl-glycyl sequences in both repressors, and in both repressors, the cleavage separates the repressor's NH2-terminal DNA-binding domain from its COOH-terminal oligomerization domain. A papain-generated proteolytic fragment of lambda repressor consisting of repressor residues 93-236 is also efficiently cleaved by recA protein. Moreover, the recA cleavage of radioactive lambda repressor can be inhibited by certain COOH-terminal proteolytic fragments of lambda repressor which do not contain the alanyl-glycyl cleavage sequence. These facts suggest that recA cleavage of lambda repressor requires an intact COOH-terminal domain but not an intact NH2-terminal domain.

Adenosine Triphosphatases↗
PubMed1982

Diverse effects of mutations in the signal sequence on the secretion of beta-lactamase in Salmonella typhimurium.

Mutations in the beta-lactamase structural gene that alter the signal peptide were used to study secretion into the periplasm of Salmonella typhimurium. Processing and cellular location of mutant gene products were followed by pulse-chase and cell-fractionation experiments and by trypsin accessibility in intact and lysed spheroplasts. The precursor proteins examined never appear as a free species in the periplasm. Two of the signal-sequence mutants accumulate a precursor form that is trypsin-accessible in intact spheroplasts; the precursors synthesized by the remaining mutants resemble wild-type in that they remain trypsin-inaccessible. One of the latter mutants does produce mature protein, but at a very reduced rate. It thus appears that signal-sequence mutations can affect more than one step in the secretion process, and that processing of the signal peptide is not required for the protein to be translocated (at least partially) across the inner membrane.

Amino Acid Sequence↗
PubMed1981

lambda Repressor and cro--components of an efficient molecular switch.

In a lysogen, most genes of phage lambda are repressed; in response to a transient induction signal, they are efficiently switched on. The switch, which consists in part of a tripartite operator to which two regulatory proteins bind, depends not only on DNA--protein interactions, but also on effects transmitted from one DNA-bound protein to another. lambda Exemplifies a strategy that facilitates efficient switching between two physiological states in response to a transient signal.

Animals↗
PubMed1981

Amino acid sequence of p15 from avian myeloblastosis virus complex.

The complete amino acid sequence of the p15 gag protein from avian myeloblastosis virus (AMV) complex has been determined by sequential Edman degradation of the intact molecule and of peptide fragments generated by limited tryptic cleavage, cleavage with staphylococcal protease, and cyanogen bromide cleavage. AMV p15 is a single-chain protein containing 124 amino acids. The charged amino acids tend to be clustered in the primary structure. p15 contains a single cysteine at position 113 which may be essential for the p15 associated proteolytic activity. However, p15 shows no appreciable sequence homology with papain or other classical thiol proteases.

Amino Acid Sequence↗
PubMed1981

Primary structure of the phage P22 repressor and its gene c2.

The amino acid sequence of the Salmonella phage P2 repressor and the DNA sequence of its gene c2 have been determined. Sequential Edman degradations on intact P22 repressor and repressor peptides generated by proteolytic and chemical cleavages have been overlapped to give approximately 97% of the complete protein sequence. Additionally, the nucleotide sequence of the P22 c2 repressor gene has been determined by DNA sequencing techniques. The DNA sequence and partial protein sequence are collinear and together define the complete amino acid sequence of P22 repressor. The repressor is a single-chain 216 amino acid polypeptide. Basic residues in the sequence tend to be clustered, and residues 9-20 are highly basic, containing five arginyl and three lysyl residues. The carboxyl-terminal 133 amino acids of the c2 repressor are homologous to the carboxyl-terminal sequence of the coliphage lambda cI repressor. The amino-terminal sequences of these two repressors show little similarity.

Amino Acid Sequence↗
PubMed1981

Purification and properties of alanine tRNA synthetase from Escherichia coli A tetramer of identical subunits.

Escherichia coli alanine tRNA synthetase has been purified from a strain which carries the gene on a recombinant pBR322 plasmid. Several per cent of the soluble protein can be obtained as alanine tRNA synthetase in the plasmid containing host cell. The enzyme was proven to be an alpha 4 tetramer with a Mr = 380,000 by the following criteria: i) a single band of Mr = 95,000 was found in sodium dodecyl sulfate gel electrophoresis; ii) gel filtration chromatography gives a single peak at a Mr = 360,000 for the native enzyme; iii) dimethyl suberimidate cross-linking indicates a tetrameric structure; iv) a single undecapeptide N-terminal sequence was found which is Ser-Lys-Ser-Thr-Ala-Glu-Ile-Arg-Gln-Ala-Phe. Limited proteolysis generates a fragment of the native enzyme. The fragment has a Mr = 48,000 (one half that of the native subunit) and, in contrast to the native enzyme, oligomerization of the fragment could be not detected either by gel filtration chromatography or by dimethyl suberimidate cross-linking. The fragment is derived from the NH2-terminal half of the native subunit as shown by their common decapeptide NH2-terminal amino acid sequences. The ATP-PPi exchange activity of 1 mol of fragment is identical with that of 1 mol of native subunit, but aminoacylation activity is absent from the fragment. Therefore, in the fragment, the aminoacyl adenylate formation activity is cleanly separated from tRNA aminoacylation and subunit association properties. These results also mean that, with respect to aminoacyl adenylate formation activity, each subunit in the native tetramer acts independently.

Alanine-tRNA Ligase↗
PubMed1979

The lambda repressor contains two domains.

Papain digestion of the lambda phage repressor produces two fragments that are relatively resistant to further digestion. One includes the amino terminus (residues 1-92) and the other the carboxyl terminus (residues 132-236). Calorimetry shows that the amino-terminal fragment denatures near 50 degrees C and that the carboxyl-terminal fragment denatures near 70 degrees C. Intact repressor undergoes two denaturations, one near 50 degrees C and another near 70 degrees C. These and other data show that lambda repressor consists of two domains joined by a "connector" 40 amino acids long that is sensitive to proteases. The amino-terminal domain binds DNA, and the carboxyl-terminal domain oligomerizes.

Amino Acid Sequence↗
PubMed1978

Primary structure of the lambda repressor.

The complete covalent structure of the bacteriophage lambda repressor has been determined by sequential Edman degradation, gas chromatographic-mass spectrometric peptide sequencing, and DNA sequencing of the repressor gene cI. The repressor is a single-chain, acidic protein containing 236 amino acids. The amino terminal 40 residues are highly polar and basic. Lysines and arginines in the sequence tend to be clustered.

Amino Acid Sequence↗
PubMed1974

The amino-acid sequence of the amino-terminal 37 residues of human parathyroid hormone.

The sequence of the amino-terminal 37 residues of human parathyroid hormone has been established. The hormone used in these studies was isolated in highly purified form from parathyroid adenomata and was subjected to automated degradation in a Beckman sequencer. A high-sensitivity sequencing procedure employing (35)S-labeled phenylisothiocyanate of high specific activity as the coupling agent was used. The sequence obtained differs from that of bovine parathyroid hormone in three of the first 37 positions, and from that of porcine parathyroid hormone in two positions. A single human-specific residue was found (asparagine 16). The sequence obtained differs at three positions (22, 28, and 30) from the structure for human parathyroid hormone reported recently by Brewer et al. [(1972) Proc. Nat. Acad. Sci. USA 69, 3585-3588] and synthesized by Andreatta et al. [(1973) Helv. Chim. Acta, 56, 470-473] We have carefully reviewed our data, reported here in detail, on the sequence positions in dispute. We must conclude, on the basis of all available data, that the structure that we propose is the correct structure. The objective resolution of these discrepancies in structural analysis through further chemical and immunochemical studies is important, since synthesis of human parathyroid hormone, in which there is widespread interest for physiological and clinical studies, must be based on the correct sequence of the human hormone if the peptide is to be genuinely useful.

Adenoma↗