Characterisation of Lyzls in mice and antibacterial properties of human LYZL6

Age-dependent changes in the expression and localization of LYZL4, LYZL6 and PCNA during testicular development in the Ashidan yak

Lysozyme like 4 (LYZL4), lysozyme like 6 (LYZL6) and proliferating cell nuclear antigen (PCNA) are implicated in the regulation of testicular function, but there was no research reported available on the expression patterns of LYZL4, LYZL6 and PCNA genes at different developmental stages of yak testes. In this study, we used the qRT-PCR, western blotting and immunohistochemistry estimated the LYZL4, LYZL6 and PCNA gene expression and protein lo-calization at different developmental stages of yak testes. The qPCR results showed that the mRNA expression of LYZL4, LYZL6 and PCNA genes significantly increased with age in the testes of yaks. Western blot results showed that the protein abundance of LYZL4, LYZL6 and PCNA in yak testes was significantly higher after puberty than before puberty. Furthermore, the results of immunohistochemistry indicated that LYZL4, LYZL6 and PCNA may be involved in the regulation of spermatogonia proliferation and Leydig cell function in immature testis. In adult yak testes, LYZL4, LYZL6 and PCNA may involve in the development of round spermatids and primary spermatocytes during testicular development. Our results indicated that LYZL4, LYZL6 and PCNA may be involved in the development of Sertoli cells, Leydig cells and gonocytes in yak testes.

Host defense amyloids: Biosensors of the immune system?

There is considerable evidence showing that highly ordered aggregate structures known as amyloids carry out essential biological roles in species ranging from bacteria to humans. Indeed, many antimicrobial peptides/proteins form amyloids to carry out their host defense functions and many amyloids are antimicrobial. The similarity of host defense amyloids from bacterial biofilms to the mammalian epididymal amyloid matrix implies highly conserved host defense structures/functions. With an emphasis on the epididymal amyloid matrix, here we review the common properties of host defense amyloids including unique traits that would allow them to function as powerful biosensors of the immune system.

Host defense functions of the epididymal amyloid matrix

The epididymal lumen is an immunologically distinct environment. It maintains tolerance for the naturally antigenic spermatozoa to allow their maturation into functional cells while simultaneously defending against pathogens that can ascend the male tract and cause infertility. We previously demonstrated that a nonpathological amyloid matrix that includes several cystatin-related epididymal spermatogenic (CRES) subgroup family members is distributed throughout the mouse epididymal lumen but its function was unknown. Here, we reveal a role for the epididymal amyloid matrix in host defense and demonstrate that the CRES amyloids and CD-1 mouse epididymal amyloid matrix exhibit potent antimicrobial activity against bacterial strains that commonly cause epididymal infections in men. We show the CRES and epididymal amyloids use several defense mechanisms including bacterial trapping, disruption of bacterial membranes and promotion of unique bacterial ghost-like structures. Remarkably, these antimicrobial actions varied depending on the bacterial strain indicating CRES amyloids and the epididymal amyloids elicit strain-specific host defense responses. We also demonstrate that the CRES monomer and immature assemblies of the epididymal amyloid transitioned into advanced structures in the presence of bacteria, suggesting their amyloid-forming/shape-shifting properties allows for a rapid reaction to a pathogen and provides an inherent plasticity in their host defense response. Together, our studies reveal new mechanistic insight into how the male reproductive tract defends against pathogens. Future studies using a mouse model for human epididymitis are needed to establish the epididymal amyloid responses to pathogens in vivo. Broadly, our studies provide an example of why nature has maintained the amyloid fold throughout evolution.

Applications of Lysozyme, an Innate Immune Defense Factor, as an Alternative Antibiotic

Lysozyme is a ~14 kDa protein present in many mucosal secretions (tears, saliva, and mucus) and tissues of animals and plants, and plays an important role in the innate immunity, providing protection against bacteria, viruses, and fungi. Three main different types of lysozymes are known: the c-type (chicken or conventional type), the g-type (goose type), and the i-type (invertebrate type). It has long been the subject of several applications due to its antimicrobial properties. The problem of antibiotic resistance has stimulated the search for new molecules or new applications of known compounds. The use of lysozyme as an alternative antibiotic is the subject of this review, which covers the results published over the past two decades. This review is focused on the applications of lysozyme in medicine, (the treatment of infectious diseases, wound healing, and anti-biofilm), veterinary, feed, food preservation, and crop protection. It is available from a wide range of sources, in addition to the well-known chicken egg white, and its synergism with other compounds, endowed with antimicrobial activity, are also summarized. An overview of the modified lysozyme applications is provided in the form of tables.

Recombinant expression and molecular characterization of buffalo sperm lysozyme-like protein 1

Several sperm lysozyme-like genes evolved from lysozyme by successive duplications and mutations; however their functional role in the reproduction of farm animals is not well understood. To understand the function and molecular properties of buffalo sperm lysozyme-like protein 1 (buSLLP1), it was expressed in E. coli; however, it partitioned to inclusion bodies. Lowering of temperature and inducer concentration did not help in the recovery of the expressed protein in the biologically active form. Therefore, buSLLP1 was cloned and expressed in Pichiapink system based on auxotrophic Pichia pastoris in a labscale fermenter. The expressed protein was obtained in flow-through by using a 30 kDa ultrafiltration membrane followed by MonoQ anion exchange chromatography, resulting in a homogenous preparation of 40 mg recombinant buSLLP1 per liter of initial spent culture-supernatant. Circular dichroism spectroscopy showed that recombinant buSLLP1 possessed a native-like secondary structure. The recombinant buSLLP1 also showed thermal denaturation profile typical of folded globular proteins; however, the thermal stability was lower than the hen egg white lysozyme. Binding of buSLLP1 to chitin and zona pellucida of buffalo oocytes showed that the recombinant buSLLP1 possessed a competent binding pocket, therefore, the produced protein could be used to study its functional role in the reproduction of farm animals.

A mouse seminal vesicle-secreted lysozyme c-like protein modulates sperm capacitation

Lysozyme (LYZ) c-like proteins are primarily present in the testis and epididymis of male reproductive tissues. Here, we report a novel member of the c-type LYZ family, the seminal vesicle-secreted LYZ c-like protein (SVLLP). Three forms of SVLLP were purified from mouse seminal vesicle secretions and characterized as glycoproteins with the same protein core but different N-linked glycans. SVLLP is structurally similar to c-type LYZ proteins. Only one of the 20 invariant residues was altered in the consensus sequence of c-type LYZs; however, the changed residue (N53S) is one of two essential catalytic residues. LYZ activity assays demonstrated that the three glycoforms of SVLLP lacked enzyme activity. SVLLP is primarily expressed in seminal vesicles. Immunohistochemistry revealed that it occurs in the luminal fluid and mucosal epithelium of the seminal vesicles. Testosterone is not the primary regulator for its expression in the seminal vesicle. SVLLP binds to sperm and suppresses bovine serum albumin-induced sperm capacitation, inhibits the acrosome reaction, and blocks sperm-oocyte interactions in vitro, suggesting that SVLLP is a sperm capacitation inhibitor.

Associations of Genetic Variants Contributing to Gut Microbiota Composition in Immunoglobin A Nephropathy

The gut microbiota and host genetics are implicated in the pathogenesis of IgAN. Recent studies have confirmed that microbial compositions are heritable (microbiome quantitative trait loci [QTL]).

The gut microbiota has been implicated in immunoglobin A nephropathy (IgAN) because the intestinal immune response is assumed to be one of the disease triggers. Since the microbial composition is heritable, we hypothesize that genetic variants controlling gut microbiota composition may be associated with susceptibility to IgAN or clinical phenotypes. A total of 175 gut-microbiome-associated genetic variants were retrieved from the Genome-Wide Association Study (GWAS) Catalog. Genetic associations were examined in 1,511 patients with IgAN and 4,469 controls. Subphenotype associations and microbiome annotations were undertaken for a better understanding of how genes shaped phenotypes. Likely candidate microbes suggested in genetic associations were validated using 16S rRNA gene sequencing in two independent data sets with 119 patients with IgAN and 45 controls in total. Nine genetic variants were associated with susceptibility to IgAN. Risk genotypes of LYZL1 were associated with higher serum levels of galactose-deficient IgA1 (Gd-IgA1). Other significant findings included the associations between the risk genotype of SIPA1L3 and early age at onset, PLTP and worse kidney function, and AL365503.1 and more severe hematuria. Besides, risk genotypes of LYZL1 and SIPA1L3 were associated with decreased abundances of Dialister and Bacilli, respectively. Risk genotypes of PLTP and AL365503.1 were associated with increased abundances of Erysipelotrichaceae and Lachnobacterium, respectively. 16S data validated a decreased tendency for Dialister and an increased tendency for Erysipelotrichaceae in IgAN. In this pilot study, our results provided preliminary evidence that the gut microbiota in IgAN was affected by host genetics and shed new light on candidate bacteria for future pathogenesis studies.

IMPORTANCE The gut microbiota and host genetics are implicated in the pathogenesis of IgAN. Recent studies have confirmed that microbial compositions are heritable (microbiome quantitative trait loci [QTL]). The relationship between host genetics and the microbiota and the role of the microbiota in IgAN are unclear. We retrieved the GWAS Catalog and associated microbiome QTL in IgAN, observing that nine genetic variants were associated with IgAN susceptibility and some clinical phenotypes. In a consistent way, the decreased abundance of Dialister was associated with higher serum levels of Gd-IgA1, and 16S rRNA gene analysis confirmed the decreased abundance of Dialister in IgAN. These data provided preliminary evidence that the gut microbiota in IgAN was affected by host genetics, which is a new strategy for future pathogenesis and intervention studies.

Comprehensive functional enrichment analysis of male infertility

Spermatogenesis is a multifactorial process that forms differentiated sperm cells in a complex microenvironment. This process involves the genome, epigenome, transcriptome, and proteome to ensure the stability of the spermatogonia and supporting cells. The identification of signaling pathways linked to infertility has been hampered by the inherent complexity and multifactorial aspects of spermatogenesis. Systems biology is a promising approach to unveil underlying signaling pathways and genes and identify putative biomarkers. In this study, we analyzed thirteen microarray libraries of infertile humans and mice, and different classes of male infertility were compared using differentially expressed genes and functional enrichment analysis. We found regulatory processes, immune response, glutathione transferase and muscle tissue development to be among the most common biological processes in up-regulated genes, and genes involved in spermatogenesis were down-regulated in maturation arrest (MArrest) and oligospermia cases. We also observed the overexpression of genes involved in steroid metabolism in post-meiotic and meiotic arrest. Furthermore, we found that the infertile mouse model most similar to human MArrest was the Dazap1 mutant mouse. The results of this study could help elucidate features of infertility etiology and provide the basis for diagnostic markers.

LYZL6, an acidic, bacteriolytic, human sperm-related protein, plays a role in fertilization

Lysozyme-like proteins (LYZLs) belong to the c-type lysozyme/α-lactalbumin family and are selectively expressed in the mammalian male reproductive tract. Two members, human sperm lysozyme-like protein (SLLP) -1 and mouse LYZL4, have been reported to contribute to fertilization but show no bacteriolytic activity. Here, we focused on the possible contribution of LYZL6 to immunity and fertilization. In humans, LYZL6 was selectively expressed by the testis and epididymis and became concentrated on spermatozoa. Native LYZL6 isolated from sperm extracts exhibited bacteriolytic activity against Micrococcus lysodeikticus. Recombinant LYZL6 (rLYZL6) reached its peak activity at pH 5.6 and 15 mM of Na+, and could inhibit the growth of Gram-positive, but not Gram-negative bacteria. Nevertheless, the bacteriolytic activity of rLYZL6 proved to be much lower than that of human lysozyme under physiological conditions. Immunodetection with a specific antiserum localized the LYZL6 protein on the postacrosomal membrane of mature spermatozoa. Immunoneutralization of LYZL6 significantly decreased the numbers of human spermatozoa fused with zona-free hamster eggs in a dose-dependent manner in vitro. Thus, we report here for the first time that LYZL6, an acidic, bacteriolytic and human sperm-related protein, is likely important for fertilization but not for the innate immunity of the male reproductive tract.

Expression profile of SPACA5/Spaca5 in spermatogenesis and transitional cell carcinoma of the bladder

The majority of bladder cancer-associated mortalities are due to transitional cell carcinoma (TCC), which is the most prevalent and chemoresistant malignancy of the bladder. Sperm acrosome associated 5 (SPACA5)/Spaca5 is a sperm acrosome-associated, c-type lysozyme-like protein that has been recently identified, and has been designated as an attractive candidate antigen for cancer testis. In the present study, the expression profile of SPACA5/Spaca5 was analyzed in spermatogenesis and TCC of the bladder using diverse molecular and cellular biology methods. Using reverse transcription-polymerase chain reaction (RT-PCR) to analyze the multi-tissue distribution and temporal expression of SPACA5/Spaca5, the SPACA5/Spaca5 gene was determined to be generally not expressed in normal tissue, with the exception of the testis, and it could be detected at a low level on day 20 after birth in mouse testes and at a higher level on day 28. Immunohistochemistry staining revealed that the SPACA5/Spaca5 protein was exclusively observed in the elongated spermatid of the normal testes, and was ectopically expressed in the cytoplasm of TCC, while it was not expressed in normal bladder tissues. The frequency of SPACA5 messenger RNA was detected in 45% of TCC (9/20) by RT-quantitative PCR. Furthermore, SPACA5 protein was more frequently detected in high-grade than in low-grade tumors (61.54 vs. 30.00%, P=0.035). Accordingly, high SPACA5 staining scores were observed to be significantly associated with high-grade tumors (n=65, R=0.279, P=0.027). Collectively, our findings indicated that SPACA5/Spaca5 may be important in male spermatogenesis and may be used as a potential target for specific immunotherapy in patients suffering from TCC.

Structural, Functional and Phylogenetic Analysis of Sperm Lysozyme-Like Proteins

Sperm lysozyme-like proteins belonging to c-type lysozyme family evolved in multiple forms. Lysozyme-like proteins, viz., LYZL2, LYZL3 or SLLP1, LYZL4, LYZL5 and LYZL6 are expressed in the testis of mammals. Not all members of LYZL family have been uniformly and unambiguously identified in the genome and proteome of mammals. Some studies suggested a role of SLLP1 and LYZL4 in fertilization; however, the function of other LYZL proteins is unknown. We identified all known forms of LYZL proteins in buffalo sperm by LC-MS/MS. Cloning and sequence analysis of the Lyzl cDNA showed 38-50% identity at amino acid level among the buffalo LYZL paralogs, complete conservation of eight cysteines and other signature sequences of c-type lysozyme family. Catalytic residues in SLLP1, LYZL4 and LYZL5 have undergone replacement. The substrate binding residues showed significant variation in LYZL proteins. Residues at sites 62, 101, 114 in LYZL4; 101 in SLLP1; 37, 62, and 101 in LYZL6 were more variable among diverse species. Sites 63 and 108 occupied by tryptophan were least tolerant to variation. Site 37 also showed lower tolerance to substitution in SLLP1, LYZL4 and LYZL5, but more variable in non-testicular lysozymes. Models of LYZL proteins were created by homology modeling and the substrate binding pockets were analyzed in term of binding energies and contacting residues of LYZL proteins with tri-N-acetylglucosamine (NAG)3 in the A-B-C and B-C-D binding mode. Except LYZL6, LYZL proteins did not show significant difference in binding energies in comparison to hen egg white lysozyme in the A-B-C mode. (NAG)3 binding energy in the B-C-D mode was higher by 1.3-2.2 kcal/mol than in A-B-C mode. Structural analysis indicated that (NAG)3 was involved in making more extensive interactions including hydrogen bonding with LYZL proteins in B-C-D mode than in A-B-C mode. Despite large sequence divergence among themselves and with respect to c-type lysozymes, substrate binding residues as well as hydrogen bonding network between (NAG)3 and proteins were mostly conserved. LYZL5 in buffalo and other mammalian species contained additional 10-12 amino acid sequence at c-terminal that matched with ankyrin repeat domain-containing protein 27. Phylogenetic analysis indicated LYZL2 to be most ancient among all the LYZL proteins and that the evolution of LYZL proteins occurred through several gene duplications preceding the speciation of mammals from other vertebrates as distant as reptiles and amphibians.

In Silico and Biochemical Characterization of Lysozyme-Like Proteins in the Rat

Background

Spermatogenesis and sperm maturation in the male reproductive tract is dictated by a variety of proteins secreted in the testis and epididymis. Though the proteome of these tissues is known, the functional role of many of these proteins remains uncharacterized. In this study, we characterize the rat Lysozyme-like (Lyzl) genes and proteins.

Methods

In silico tools were used to predict the primary, secondary and tertiary structures. Reverse transcription PCR, immunofluorescence and immunoblotting were used to determine the expression pattern. Lysozyme like enzyme activity was assessed by standard assays.

Results

Six rat Lyzl genes namely Lyzl1, Lyzl3, Lyzl4, Lyzl5, Lyzl6 and Lyzl7 were found to be highly conserved among the vertebrates with higher homology to mouse counterparts than with human counterparts. All the LYZL proteins contained the characteristic 4 disulfide bridges similar to c-type lysozyme. Only LYZL 1 and 6, conserved the active site amino acids of the lysozyme. Molecular modeling studies indicated that LYZL proteins exhibit strikingly similar three-dimensional structures among themselves. The secondary structure analysis of the recombinant LYZL proteins indicated the presence of α-helix, β-sheet and random coil with α-helix being the majority. Docking studies indicated the peptidoglycan binding nature of LYZL proteins. All the rat Lyzl mRNA transcripts (Lyzl1, Lyzl3, Lyzl4, Lyzl5, Lyzl6 and Lyzl7) are predominantly expressed in testes though some of them are expressed in tissues other than reproductive tract. Their expression was androgen independent. The rat LYZL proteins are localized in the germinal epithelium and on the spermatozoa. Recombinant LYZL1 and 6 possessed muramidase, isopeptidase and antibacterial activities. The mechanism of antibacterial action of LYZL1 and LYZL6 involved bacterial membrane damage and leakage of cellular contents. Only LYZL1 and 6 possess peptidoglycan binding ability, whereas LYZL3, LYZL4 and LYZL5 possess hyaluronan binding ability suggesting a possible functional divergence of these proteins. LYZL3, LYZL4 and LYZL7 possessed free radical scavenging property, suggesting that they may act as antioxidants.

Conclusion

The divergent properties of LYZL proteins indicate that they may have a role in sperm function, innate immunity and other physiological process as well.

Identification of bovine sperm acrosomal proteins that interact with a 32-kDa acrosomal matrix protein

Mammalian fertilization is accomplished by the interaction between sperm and egg. Previous studies from this laboratory have identified a stable acrosomal matrix assembly from the bovine sperm acrosome termed the outer acrosomal membrane-matrix complex (OMC). This stable matrix assembly exhibits precise binding activity for acrosin and N-acetylglucosaminidase. A highly purified OMC fraction comprises three major (54, 50, and 45 kDa) and several minor (38-19 kDa) polypeptides. The set of minor polypeptides (38-19 kDa) termed "OMCrpf polypeptides" is selectively solubilized by high-pH extraction (pH 10.5), while the three major polypeptides (55, 50, and 45 kDa) remain insoluble. Proteomic identification of the OMC32 polypeptide (32 kDa polypeptide isolated from high-pH soluble fraction of OMC) yielded two peptides that matched the NCBI database sequence of acrosin-binding protein. Anti-OMC32 recognized an antigenically related family of polypeptides (OMCrpf polypeptides) in the 38-19-kDa range with isoelectric points ranging between 4.0 and 5.1. Other than glycohydrolases, OMC32 may also be complexed to other acrosomal proteins. The present study was undertaken to identify and localize the OMC32 binding polypeptides and to elucidate the potential role of the acrosomal protein complex in sperm function. OMC32 affinity chromatography of a detergent-soluble fraction of bovine cauda sperm acrosome followed by mass spectrometry-based identification of bound proteins identified acrosin, lactadherin, SPACA3, and IZUMO1. Co-immunoprecipitation analysis also demonstrated the interaction of OMC32 with acrosin, lactadherin, SPACA3, and IZUMO1. Our immunofluorescence studies revealed the presence of SPACA3 and lactadherin over the apical segment, whereas IZUMO1 is localized over the equatorial segment of Triton X-100 permeabilized cauda sperm. Immunoblot analysis showed that a significant portion of SPACA3 was released after the lysophosphatidylcholine (LPC)-induced acrosome reaction, whereas the IZUMO1 and lactadherin polypeptides remain associated to the particulate fraction. Almost entire population of bovine sperm IZUMO1 relocates to the equatorial segment during the LPC-induced acrosome reaction. We propose that the interaction of OMC32 matrix polypeptide with detergent-soluble acrosomal proteins regulates the release of hydrolases/other acrosomal protein(s) during the acrosome reaction.