The NH2-terminal cleavage of Escherichia coli translational initiation factor IF3. A mechanism to control the intracellular level of the factor?

A short form of Escherichia coli translational initiation factor IF3, repeatedly found both in vivo and in vitro, lacking the positively charged N-terminal hexapeptide has been produced by mild trypsinization. The properties of this short form of IF3 have been studied. Compared to the long native form of the factor, the shortened IF3 displays a markedly decreased thermal stability and affinity for the 30 S ribosomal subunit, as well as a reduced biological activity in protein synthesis. Following the loss of the N-terminal hexapeptide, a second peptide bond (Lys-90-Val-91) becomes easily accessible to proteolytic attack suggesting that formation of the short IF3 may be the first step in the physiological degradation of the factor.     

Organization and nucleotide sequence of the genes for ribosomal protein S2 and elongation factor Ts in Spirulina Platensis

A 6.5 kb region from the genome of the cyanobacterium Spirulina platensis was cloned using as a probe the Escherichia coli gene for ribosomal protein S2. Sequence analysis revealed, in this region, the presence of the gene for ribosomal protein S2 and part of the gene for the elongation factor Ts (EF-Ts). The arrangement rpsB-spacer-tsf resembles that reported for E. coli. The deduced amino acid sequences of the platensis S2 and EF-Ts show significant homology with the E. coli counterparts.     

Identification, cloning, nucleotide sequence and chromosomal map location of hns, the structural gene for Escherichia coli DNA-binding protein H-NS

Summary Beginning with a synthetic oligonucleotide probe derived from its amino acid sequence, we have identified, cloned and sequenced the hns gene encoding H-NS, an abundant Escherichia coli 15 kDa DNA-binding protein with a possible histone-like function. The amino acid sequence of the protein deduced from the nucleotide sequence is in full agreement with that determined for H-NS. By comparison of the restriction map of the cloned gene and of its neighboring regions with the physical map of E. coli K12 as well as by hybridization of the hns gene with restriction fragments derived from the total chromosome, we have located the hns gene oriented counterclockwise at 6.1 min on the E. coli chromosome, just before an IS30 insertion element.     

Structure-function relationship in Escherichia coli translational initiation factors. Characterization of IF1 by high-resolution 1H-NMR spectroscopy

Escherichia coli translational initiation factor IF1 was studied by 1H-NMR spectroscopy at 400 MHz. IF1 displays a very well resolved spectrum in both aromatic and aliphatic regions. Other spectral characteristics include relatively narrow resonance lines and lack of relevant cross-relaxation phenomena. The resonances of the aromatic residues, in particular of the two His and two Tyr, were assigned by selective chemical modifications and spectroscopic techniques to individual residues in the protein sequence. The relative mobility of various residues of IF1 has been evaluated on the basis of the spin-lattice relaxation times which are rather short and homogeneous. Overall the factor appears to have a complex secondary and tertiary structure and to be a flexible protein whose residues have a high degree of internal mobility.     

Circular dichroism analysis of the ribosomal binding of initiation factor IF-3

The circular dichroism spectra of Escherichia coli 30 S ribosomal subunits have been determined between 200 and 320 nm in the presence and in the absence of initiation factor IF-3. The addition of IF-3 did not produce any major alteration of the circular dichroism spectrum of the 30 S subunits between 320 and 240 nm, but resulted in an increase of the negative ellipticity between 240 and 205 nm. The effect was maximal for an IF-3:30 S molar ratio of approximately one, and further addition of IF-3 did not lead to a further increase of ellipticity. A similar effect was not seen when the 30 S ribosomal subunits were previously heat-inactivated to destroy their IF-3 binding capacity. These data indicate that the ribosomal binding of IF-3 may be accompanied by an increase in the secondary structure of the ribosomal proteins, but does not involve any major net change in the secondary structure of the rRNA.     

SERS‐based biosensor for Alzheimer disease evaluation through the fast analysis of human serum

Alzheimer disease (AD) is the most common form of dementia in the elderly, progressively affecting the cognitive functions with a complex diagnostic procedure that limits the time for a prompt intervention. In this study we optimized a reliable protocol for the analysis of AD patients and healthy subjects' serum using the Surface Enhanced Raman Spectroscopy (SERS), taking into consideration the effect of different variables on the final spectra, analyzed and compared through multivariate analysis and correlated with hippocampus volume. As results, we demonstrated a statistical difference between the spectra collected from the two investigated groups, with an accuracy, precision and specificity of respectively 83%, 86%, and 86%. The correlation of these data with those obtained from MRI, demonstrated a direct correlation between Raman spectra and hippocampus degeneration showing the Raman Spectroscopy (RS) as a potential tool for the monitoring of AD progression and rehabilitation treatments.