Protein and Peptide Letters - Volume 29, Issue 3, 2022

Background: Pseudomonas citronellolis SJTE-3 can efficiently degrade 17β-estradiol (E2) and other estrogenic chemicals. However, the enzyme responsible for E2 metabolism within strain SJTE-3 has remained unidentified. Objective: Here, a novel 3-oxoacyl-(acyl-carrier protein) (ACP) reductase, HSD-X1 (WP_ 009617962.1), was identified in SJTE-3 and its enzymatic characteristics for the transformation of E2 were investigated. Methods: Multiple sequence alignment and homology modelling were used to predict the protein structure of HSD-X1. The concentrations of different steroids in the culture of recombinant strains expressing HSD-X1 were determined by high performance liquid chromatography. Additionally, the transcription of hsd-x1 gene was investigated using reverse transcription and quantitative PCR analysis. Heterologous expression and affinity purification were used to obtain recombinant HSD- X1. Results: The transcription of hsd-x1 gene in P. citronellolis SJTE-3 was induced by E2. Multiple sequence alignment (MSA) indicated that HSD-X1 contained the two consensus regions and conserved residues of short-chain dehydrogenase/reductases (SDRs) and 17β-hydroxysteroid dehydrogenases (17β-HSDs). Over-expression of hsd-x1 gene allowed the recombinant strain to degrade E2. Recombinant HSD-X1 was purified with a yield of 22.15 mg/L and used NAD+ as its cofactor to catalyze the oxidization of E2 into estrone (E1) while exhibiting a Km value of 0.025 ± 0.044 mM and a Vmax value of 4.92 ± 0.31 mM/min/mg. HSD-X1 could tolerate a wide range of temperature and pH, while the presence of divalent ions exerted little influence on its activity. Further, the transformation efficiency of E2 into E1 was over 98.03% across 15 min. Conclusion: Protein HSD-X1 efficiently catalyzed the oxidization of E2 and participated in estrogen degradation by P. citronellolis SJTE-3.

Being an essential enzyme in protein synthesis, the aminoacyl-tRNA synthetases (aaRSs) have a conserved function throughout evolution. However, research has uncovered altered expressions as well as interactions of aaRSs, in league with aaRS-interacting multi-functional proteins (AIMPs), forming a multi-tRNA synthetase complex (MSC) and divulging into their roles outside the range of protein synthesis. In this review, we have directed our focus into the rudimentary structure of this compact association and also how these aaRSs and AIMPs are involved in the maintenance and progression of lung cancer, the principal cause of most cancer-related deaths. There is substantial validation that suggests the crucial role of these prime housekeeping proteins in lung cancer regulation. Here, we have addressed the biological role that the three AIMPs and the aaRSs play in tumorigenesis, along with an outline of the different molecular mechanisms involved in the same. In conclusion, we have introduced the potentiality of these components as possible therapeutics for the evolution of new-age treatments of lung tumorigenesis.

Post-translational modifications (PTMs) of proteins influence protein degradation, protein- protein interactions, expression of genes, and intracellular signal transduction, thereby regulating major life processes. Among the PTMs occurring within the cytoplasm and nucleus, the most commonly studied one is the arginine methylation of proteins catalyzed by PRMTs. PRMT1 is the most excellent and extensively studied member of the PRMT family. PRMT1 occurs in various isoforms, and the unique sequence splicing of each of these isoforms encodes differential proteins that exhibit different cellular localization, substrate specificity, and enzyme activity. In addition to methylating histones, PRMT1 also methylates a large number of non-histone substrates that regulate a broad range of cellular processes. In recent years, research has revealed an increasing number of pathological diseases caused by the misregulation and aberrant expression of PRMT1, demonstrating the potential of PRMT1 as an effective biomarker for drug targets. In this context, the present study discusses the structural characteristics and the biological functions of PRMT1. Practical Applications: Several diseases originate from aberrant post-translational modifications. The misregulation of the arginine methylation of proteins, which is regulated by PRMTs and influences a series of cellular activities, leads to developmental abnormalities and physiological diseases. PRMT1, which accounts for 85% of the activity of PRMTs, is involved in several cellular processes occurring in various diseases. Multiple inhibitors have been developed and studied for their potential as biomarkers and suitable drug targets in clinical application. The present report summarizes the findings of the most recent studies focusing on the structural characteristics, splicing, substrates, and biological functions of PRMT1, to contribute to future research for deciphering the molecular mechanisms of PRMT1 and drug improvement.

Yeast Saccharomyces cerevisiae is a good eukaryotic model for studying the molecular mechanism of toxic metal ion stress. Numerous studies have been performed on the signal transduction induced by toxic metal ion stress. The physiological process of eukaryotic cells has been studied, and various stress factors have been elucidated by constructing a gene deletion library. The sensitivity and tolerance mechanism of yeast under metal ion stress has been widely studied. The sensitive genes induced by metal ion stress will provide a key foundation for studying the gene function of eukaryotic organisms. In addition, the functions of genes in response to metal ion stress mainly participate in regulating ion homeostasis, high glycerin pathway, vacuole protein separation pathway, cell wall integrity pathway, and cell autophagy. However, the interaction of these signal pathways and the detailed response mechanism need to be further studied. In addition, the technique of genomics and proteomics will help study the detailed molecular mechanism induced by toxic metal ion stress. Thus, the sensitive genes related to various signal pathways under toxic metal ion stress will be reviewed in the yeast S. cerevisiae.

Background: Alternative reading frame (ARF) protein up-regulates the intracellular level of a tumour suppressor protein, p53, by blocking MDM2 mediated p53 ubiquitination. The two homologous forms of ARF proteins are p19ARF in mice and p14ARF in humans. In our study, p19ARF-derived peptide ARF (26-44) and its cell-penetrating peptide conjugate Tat-ARF (26-44), p14ARF-derived peptide ARF (1-22), and its NrLS conjugate ARF (1-22)-NrLS were designed, and their anticancer properties were investigated. Objective: Our objective is to study the anticancer and antimicrobial properties of ARF-derived peptides and their cell-penetrating and NrLS conjugates. Methods : Peptides synthesized using solid-phase peptide synthesis (SPPS) were purified using RPHPLC and characterized using Bruker MALDI-TOF mass spectrometry. Cytotoxicity was evaluated on HeLa and BE(2)-C cells by cell viability IC50 determination. Minimum inhibitory concentrations (MIC) were determined by the broth microdilution method. Morphological studies were carried out using SEM and TEM techniques, live/dead staining, ROS and Hoest staining. Results: Peptides Tat-ARF (1-22) and ARF (1-22)-NrLS exhibited potent cytotoxic effects, comparable to the known standard cisplatin. Cellular morphological studies showed signs of apoptosis which were confirmed by reactive oxygen species (ROS) generation and Hoechst nuclear staining. ARF peptides showed potent antimicrobial activities at low micromolar concentrations without haemolysis. Conclusion : Tat modification improved the activity of ARF (26-44) by 9 folds against HeLa and 5 folds against BE(2)-C cells. NrLS modification of ARF (1-22) imparted 12 fold potency against HeLa and 2-fold potency against BE(2)-C cells. This study helps to further understand the effect of these peptides on MDM2 proteins and their role in the apoptosis signalling pathway.

Introduction: Disease causing missense mutations (DCMMs) destabilize protein structures. However it is not known how they impact the intrinsically disordered regions (IDRs) as these regions do not adopt stable 3D structures under physiological conditions. It is therefore imperative to investigate the effect of DCMMs on the functionally important IDRs. Objective: To investigate impact of DCMMs on functionally important IDRs in human proteins. Methods: We investigated the impact of the known DCMMs on three IDRs: a) an IDR with CRIB motif from WAS protein , b) a proline rich IDR of p22 protein and c) an IDR horboring TRM motif from SH3BP2 protein. Both the wild type and the mutant forms were subjected to detailed structural investigations using MD simulations for 100ns. Results: MD studies revealed that the mutants adopt fewer conformational states as compared with their wild-type counterparts of which one or two form the dominant conformational states. This result was also corroborated by the free-energy landscapes of the mutants with a fewer minima as compared with the wild-types. It was also observed that the side chains of the mutated amino acid residues introduce new hydrogen bonding interactions that stabilize one or two of the dominant conformational states. Conclusion: Our studies, thus, revealed that the disease causing missense mutations reduce the conformational heterogeneity of the intrinsically disordered proteins and furthermore, they are “locked” in one or two of those conformational states that presumably disfavour binding of the IDRs with their cognate interacting partners.

Background: Lactoferricin peptide (LP) has been reported to control cancer cell proliferation. NF-ΚB interacting lncRNA (NKILA) is a tumor suppressor in several cancers. Objective: We aimed to explore the potential function of the truncated LP (TLP) in the prevention of cervical cancer cell proliferation. Methods: Bioinformatics analysis via PPA-Pred2 showed that 18-aa N-terminus of truncated lactoferricin peptide (TLP18, FKCRRWQWRMKKLGAPSI) shows higher affinity with nuclear factor kappaB (NF-ΚB) than LP. The effects of LP and TLP18 on cervical cancer cells SiHa and HeLa and the related mechanisms were explored by investigating NF-ΚB and lncRNA-NKILA. Results: TLP18 shows an inhibitory rate up to 0.4-fold higher than LP on the growth of cervical cancer cells (P<0.05). NKILA siRNA promoted cell growth whether LP or TLP18 treatment (P<0.05). TLP18 treatment increases the level of lncRNA-NKILA and reduces the level of NF-ΚB up to 0.2-fold and 0.6-fold higher than LP (P<0.05), respectively. NKILA siRNA increased the levels of NF-ΚB, cleaved caspase-3, and BAX (P<0.05). TLP18 increased apoptotic cell rate up to 0.2-fold higher than LP, while NKILA siRNA inhibited cell apoptosis cell growth even LP or TLP18 treatment. Conclusion: Truncated Lactoferricin peptide controls cervical cancer cell proliferation via lncRNA- NKILA/NF-ΚB feedback loop.