Gene cloning of chitinase A1 from Bacillus circulans WL-12 revealed its evolutionary relationship to Serratia chitinase and to the type III homology units of fibronectin

Characterization of the extracellular domain of sensor histidine kinase NagS from Paenibacillus sp. str. FPU-7: nagS interacts with oligosaccharide binding protein NagB1 in complexes with N, N'-diacetylchitobiose

We have previously isolated the Gram-positive chitin-degrading bacterium Paenibacillus sp. str. FPU-7. This bacterium traps chitin disaccharide (GlcNAc)2 on its cell surface using two homologous solute-binding proteins, NagB1 and NagB2. Bacteria use histidine kinase (HK) of the two-component regulatory system as an extracellular environment sensor. In this study, we found that nagS, which encodes a HK, is located next to the nagB1 gene. Biochemical experiments revealed that the NagS sensor domain (NagS30-294) interacts with the NagB1-(GlcNAc)2 complex. However, proof of NagS30-294 interacting with NagB1 without (GlcNAc)2 is currently unavailable. In contrast to NagB1, no complex formation was observed between NagS30-294 and NagB2, even in the presence of (GlcNAc)2. The NagS30-294 crystal structure at 1.8 Å resolution suggested that the canonical tandem-Per-Arnt-Sim fold recognizes the NagB1-(GlcNAc)2 complex. This study provides insight into the recognition of chitin oligosaccharides by bacteria.

Bioconversion of chitin into chitin oligosaccharides using a novel chitinase with high chitin-binding capacity

Chitin is the second largest renewable biomass resource in nature, it can be enzymatically degraded into high-value chitin oligosaccharides (CHOSs) by chitinases. In this study, a chitinase (ChiC8-1) was purified and biochemically characterized, its structure was analyzed by molecular modeling. ChiC8-1 had a molecular mass of approximately 96 kDa, exhibited its optimal activity at pH 6.0 and 50 °C. The K_m and V_max values of ChiC8-1 towards colloidal chitin were 10.17 mg mL^-1 and 13.32 U/mg, respectively. Notably, ChiC8-1 showed high chitin-binding capacity, which may be related to the two chitin binding domains in the N-terminal. Based on the unique properties of ChiC8-1, a modified affinity chromatography method, which combines protein purification with chitin hydrolysis process, was developed to purify ChiC8-1 while hydrolyzing chitin. In this way, 9.36 ± 0.18 g CHOSs powder was directly obtained by hydrolyzing 10 g colloidal chitin with crude enzyme solution. The CHOSs were composed of 14.77-2.83 % GlcNAc and 85.23-97.17 % (GlcNAc)₂ at different enzyme-substrate ratio. This process simplifies the tedious purification and separation steps, and may enable its potential application in the field of green production of chitin oligosaccharides.

Role of the FnIII domain associated with a cell wall-degrading enzyme cellobiosidase of Xanthomonas oryzae pv. oryzae

Cellobiosidase (CbsA) is an important secreted virulence factor of Xanthomonas oryzae pv. oryzae (Xoo), which causes bacterial blight of rice. CbsA is one of several cell wall-degrading enzymes secreted by Xoo via the type II secretion system (T2SS). CbsA is considered a fundamental virulence factor for vascular pathogenesis. CbsA has an N-terminal glycosyl hydrolase domain and a C-terminal fibronectin type III (FnIII) domain. Interestingly, the secreted form of CbsA lacks the FnIII domain during in planta growth. Here we show that the presence of the FnIII domain inhibits the enzyme activity of CbsA on polysaccharide substrates like carboxymethylcellulose. The FnIII domain is required for the interaction of CbsA with SecB chaperone, and this interaction is crucial for the stability and efficient transport of CbsA across the inner membrane. Deletion of the FnIII domain reduced virulence similar to ΔcbsA Xoo, which corroborates the importance of the FnIII domain in CbsA. Our work elucidates a hitherto unknown function of the FnIII domain in enabling the virulence-promoting activity of CbsA.

Molecular Identification, Characterization and Improvement of A Chitinase Producing Bacillus strain Showing Significant Control against Some Dermatophytic Fungi

Bacillus bacteria are advantageous antagonistic organisms that can be used as bio-control agents. This study is aimed at screening the antagonistic activity of different strains of isolated Bacillus bacteria and molecular identification of the superior chitinase producer strain against dermatophytes fungi. Soil samples were collected from different places of Kotoor city, Gharbia Governorate, Egypt and Al Madina Al Munawwarah, Kingdom of Saudi Arabia. A collection of Bacillus isolated from soil was tested in vitro against the dermatophytes: Microsporum sp. and Trichophyton sp. The bacterial strains Kh-B1 and Kh-B2 showed the highest antagonistic activity against dermatophytes pathogenic fungi. The highest amount of chitinase productivity (13.6 units/ml) was obtained from the original Bacillus strain (Kh-B1) at 3 days of incubation. BLAST analysis of the amplified 16S ribosomal RNA gene sequence identified the Bacillus strain (Kh-B1) as Paenibacillus macerans. Upon the mutation induction by UV light, the highest chitinase-producing mutant was Kh-UVB-4 as it showed 305.88 percent production higher than the wild-type strain. While, upon the mutation induction by EMS, the highest amount of chitinase produced was 54.8 units/ml by mutant Kh-ESB-20, and it has produced 402.94% more than the original untreated strain. The application of RAPD-PCR protocol using three 15-mer random primers was used to determine the genetic effects of mutagenic treatments on the wild type strain (Kh-B1) as well as to demonstrate the genetic variability between the five most chitinase producing mutants and the wild type (Paenibacillus macerans).

Structures and functions of carbohydrate-active enzymes of chitinolytic bacteria Paenibacillus sp. str. FPU-7

Chitin and its derivatives have valuable potential applications in various fields that include medicine, agriculture, and food industries. Paenibacillus sp. str. FPU-7 is one of the most potent chitin-degrading bacteria identified. This review introduces the chitin degradation system of P. str. FPU-7. In addition to extracellular chitinases, P. str. FPU-7 uses a unique multimodular chitinase (ChiW) to hydrolyze chitin to oligosaccharides on the cell surface. Chitin oligosaccharides are converted to N-acetyl-d-glucosamine by β-N-acetylhexosaminidase (PsNagA) in the cytosol. The functions and structures of ChiW and PsNagA are also summarized. The genome sequence of P. str. FPU-7 provides opportunities to acquire novel enzymes. Genome mining has identified a novel alginate lyase, PsAly. The functions and structure of PsAly are reviewed. These findings will inform further improvement of the sustainable conversion of polysaccharides to functional materials.

Structural characterization of two solute-binding proteins for N,N'-diacetylchitobiose/N,N',N''-triacetylchitotoriose of the gram-positive bacterium, Paenibacillus sp. str. FPU-7

The chitinolytic bacterium Paenibacillus sp. str. FPU-7 efficiently degrades chitin into oligosaccharides such as N-acetyl-D-glucosamine (GlcNAc) and disaccharides (GlcNAc)2 through multiple secretory chitinases. Transport of these oligosaccharides by P. str. FPU-7 has not yet been clarified. In this study, we identified nagB1, predicted to encode a sugar solute-binding protein (SBP), which is a component of the ABC transport system. However, the genes next to nagB1 were predicted to encode two-component regulatory system proteins rather than transmembrane domains (TMDs). We also identified nagB2, which is highly homologous to nagB1. Adjacent to nagB2, two genes were predicted to encode TMDs. Binding experiments of the recombinant NagB1 and NagB2 to several oligosaccharides using differential scanning fluorimetry and surface plasmon resonance confirmed that both proteins are SBPs of (GlcNAc)2 and (GlcNAc)3. We determined their crystal structures complexed with and without chitin oligosaccharides at a resolution of 1.2 to 2.0 Å. The structures shared typical SBP structural folds and were classified as subcluster D-I. Large domain motions were observed in the structures, suggesting that they were induced by ligand binding via the "Venus flytrap" mechanism. These structures also revealed chitin oligosaccharide recognition mechanisms. In conclusion, our study provides insight into the recognition and transport of chitin oligosaccharides in bacteria.

Biochemical and molecular characterization of an acido-thermostable endo-chitinase from Bacillus altitudinis KA15 for industrial degradation of chitinous waste

This paper reports the isolation and identification of an acido-thermostable chitinase (ChiA-Ba43) which was purified, from the culture liquid of Bacillus altitudinis strain KA15, and characterized. Purification of ChiA-Ba43 produced a 69.6-fold increase in the specific activity (120,000 U/mg) of the chitinase, with a yield of 51% using colloidal chitin as substrate. ChiA-Ba43 was found to be a monomeric protein with a molecular mass of 43,190.05 Da as determined by MALDI-TOF/MS. N-terminal sequence of the first 27 amino-acids (aa) of ChiA-Ba43 displayed homology to chitinases from other Bacillus species. Interestingly, ChiA-Ba43 exhibited optimum pH and temperature of 4-5.5 and 85 °C, respectively. Thin-layer chromatography (TLC) showed that the final hydrolyzed products of the enzyme from chitin-oligosaccharides and colloidal chitin are a mixture of (GlcNAc)₂, (GlcNAc)₃, (GlcNAc)₄, and (GlcNAc)₅, which indicates that ChiA-Ba43 possesses an endo-acting function. More interestingly, compared to ChiA-Mt45, ChiA-Hh59, Chitodextrinase®, N-acetyl-β-glucosaminidase®, and ChiA-65, ChiA-Ba43 demonstrated a high level of catalytic efficiency and outstanding tolerance towards various organic solvents. The chiA-Ba43 gene (1332 bp) encoding ChiA-Ba43 (409 aa) was cloned, sequenced, and expressed in Escherichia coli strain HB101. The biochemical properties of the recombinant chitinase (rChiA-Ba43) were equivalent to those of the natively expressed enzyme. These properties make ChiA-Ba43 an ideal candidate for industrial bioconversion of chitinous waste.

High-Efficiency Secretion and Directed Evolution of Chitinase BcChiA1 in Bacillus subtilis for the Conversion of Chitinaceous Wastes Into Chitooligosaccharides

Limitations of enzyme production and activity pose a challenge for efficient degradation of chitinaceous wastes. To solve this problem, we engineered a system for high-yielding extracellular secretion of chitinase A1 from Bacillus circulans (BcChiA1) in B. subtilis. Furthermore, an innovative chitinase high-throughput screening method based on colloidal chitin stained with Remazol Brilliant Blue R (CC-RBB) was established and used to identify three mutants with improved chitinase activity: Y10A/R301A/E327A (Mu1), Y10A/D81A/E327A (Mu2), and F38A/K88A/R301A (Mu3). Their highest specific activity reached 1004.83 ± 0.87 U/mg, representing a 16.89-fold increase in activity compared to native BcChiA1. Additionally, we found that there is a synergistic effect between BcChiA1 and a lytic polysaccharide monooxygenase from Bacillus atrophaeus (BatLPMO10), which increased the chitin processing efficiency by 50% after combining the two enzymes. The yield of chitooligosaccharide (COS) production using the mutant Mu1 and BatLPMO10 reached 2885.25 ± 2.22 mg/L. Taken together, the results indicated that the CC-RBB high-throughput screening method is a useful tool for chitinase screening, and evolution of BcChiA1 in collaboration with BatLPMO10 has tremendous application potential in the biological treatment of chitinaceous wastes for COS production.

Structural and functional characterization of a glycoside hydrolase family 3 β-N-acetylglucosaminidase from Paenibacillus sp. str. FPU-7

Chitin, a β-1,4-linked homopolysaccharide of N-acetyl-d-glucosamine (GlcNAc), is one of the most abundant biopolymers on Earth. Paenibacillus sp. str. FPU-7 produces several different chitinases and converts chitin into N,N′-diacetylchitobiose ((GlcNAc)2) in the culture medium. However, the mechanism by which the Paenibacillus species imports (GlcNAc)2 into the cytoplasm and divides it into the monomer GlcNAc remains unclear. The gene encoding Paenibacillus β-N-acetyl-d-glucosaminidase (PsNagA) was identified in the Paenibacillus sp. str. FPU-7 genome using an expression cloning system. The deduced amino acid sequence of PsNagA suggests that the enzyme is a part of the glycoside hydrolase family 3 (GH3). Recombinant PsNagA was successfully overexpressed in Escherichia coli and purified to homogeneity. As assessed by gel permeation chromatography, the enzyme exists as a 57-kDa monomer. PsNagA specifically hydrolyses chitin oligosaccharides, (GlcNAc)2–4, 4-nitrophenyl N-acetyl β-d-glucosamine (pNP-GlcNAc) and pNP-(GlcNAc)2–6, but has no detectable activity against 4-nitrophenyl β-d-glucose, 4-nitrophenyl β-d-galactosamine and colloidal chitin. In this study, we present a 1.9 Å crystal structure of PsNagA bound to GlcNAc. The crystal structure reveals structural features related to substrate recognition and the catalytic mechanism of PsNagA. This is the first study on the structural and functional characterization of a GH3 β-N-acetyl-d-glucosaminidase from Paenibacillus sp.

Accelerated CO₂ Hydration with Thermostable Sulfurihydrogenibium azorense Carbonic Anhydrase-Chitin Binding Domain Fusion Protein Immobilised on Chitin Support

Carbonic anhydrases (CAs) represent a group of enzymes that catalyse important reactions of carbon dioxide hydration and dehydration, a reaction crucial to many biological processes and environmental biotechnology. In this study we successfully constructed a thermostable fusion enzyme composed of the Sulfurihydrogenibium azorense carbonic anhydrase (Saz_CA), the fastest CA discovered to date, and the chitin binding domain (ChBD) of chitinase from Bacillus circulans. Introduction of ChBD to the Saz_CA had no major impact on the effect of ions or inhibitors on the enzymatic activity. The fusion protein exhibited no negative effects up to 60 °C, whilst the fusion partner appears to protect the enzyme from negative effects of magnesium. The prepared biocatalyst appears to be thermally activated at 60 °C and could be partially purified with heat treatment. Immobilisation attempts on different kinds of chitin-based support results have shown that the fusion enzyme preferentially binds to a cheap, untreated chitin with a large crystallinity index over more processed forms of chitin. It suggests significant potential economic benefits for large-scale deployment of immobilised CA technologies such as CO₂ utilisation or mineralisation.

Characterization of the starch-acting MaAmyB enzyme from Microbacterium aurum B8.A representing the novel subfamily GH13_42 with an unusual, multi-domain organization

The bacterium Microbacterium aurum strain B8.A degrades granular starches, using the multi-domain MaAmyA α-amylase to initiate granule degradation through pore formation. This paper reports the characterization of the M. aurum B8.A MaAmyB enzyme, a second starch-acting enzyme with multiple FNIII and CBM25 domains. MaAmyB was characterized as an α-glucan 1,4-α-maltohexaosidase with the ability to subsequently hydrolyze maltohexaose to maltose through the release of glucose. MaAmyB also displays exo-activity with a double blocked PNPG7 substrate, releasing PNP. In M. aurum B8.A, MaAmyB may contribute to degradation of starch granules by rapidly hydrolyzing the helical and linear starch chains that become exposed after pore formation by MaAmyA. Bioinformatics analysis showed that MaAmyB represents a novel GH13 subfamily, designated GH13_42, currently with 165 members, all in Gram-positive soil dwelling bacteria, mostly Streptomyces. All members have an unusually large catalytic domain (AB-regions), due to three insertions compared to established α-amylases, and an aberrant C-region, which has only 30% identity to established GH13 C-regions. Most GH13_42 members have three N-terminal domains (2 CBM25 and 1 FNIII). This is unusual as starch binding domains are commonly found at the C-termini of α-amylases. The evolution of the multi-domain M. aurum B8.A MaAmyA and MaAmyB enzymes is discussed.

Molecular characterisation of Bacillus chitinase for bioconversion of chitin waste

In this work chitin was extracted chemically from shrimp shells. Seventeen Bacillus isolates were screened for chitinolytic activity. The chitinolytic strains of Bt. were screened at different temperatures and pHs for their hydrolytic potentials. By using a pair of specific primers, endochitinase gene was amplified from SBS Bt-5 strain through PCR, and then cloned into pTZ57 TA cloning vector and transferred in Escherichia coli DH5α strain. The sequenced gene (GenBank Accession No: HE995800) consists of 2031 nucleotides capable of encoding 676 residues. The protein consisted of three functional domains with a calculated molecular mass of 74.53 kDa and a pI value of 5.83. The amino acid sequence of chi gene showed 99% similarity to the genes of Bt MR11 endochitinase, Bt serovar kurstaki chitinase (kchi), Bt strain MR21 endochitinase and Bacillus cereus B4264.

The chitinase C gene PsChiC from Pseudomonas sp. and its synergistic effects on larvicidal activity

Pseudomonas sp. strain TXG6-1, a chitinolytic gram-negative bacterium, was isolated from a vegetable field in Taixing city, Jiangsu Province, China. In this study, a Pseudomonas chitinase C gene (PsChiC) was isolated from the chromosomal DNA of this bacterium using a pair of specific primers. The PsChiC gene consisted of an open reading frame of 1443 nucleotides and encoded 480 amino acid residues with a calculated molecular mass of 51.66 kDa. The deduced PsChiC amino acid sequence lacked a signal sequence and consisted of a glycoside hydrolase family 18 catalytic domain responsible for chitinase activity, a fibronectin type III-like domain (FLD) and a C-terminal chitin-binding domain (ChBD). The amino acid sequence of PsChiCshowed high sequence homology (> 95%) with chitinase C from Serratia marcescens. SDS-PAGE showed that the molecular mass of chitinase PsChiC was 52 kDa. Chitinase assays revealed that the chitobiosidase and endochitinase activities of PsChiCwere 51.6- and 84.1-fold higher than those of pET30a, respectively. Although PsChiC showed little insecticidal activity towards Spodoptera litura larvae, an insecticidal assay indicated that PsChiC increased the insecticidal toxicity of SpltNPV by 1.78-fold at 192 h and hastened death. These results suggest that PsChiC from Pseudomonas sp. could be useful in improving the pathogenicity of baculoviruses.

Degradation of Granular Starch by the Bacterium Microbacterium aurum Strain B8.A Involves a Modular α-Amylase Enzyme System with FNIII and CBM25 Domains

The bacterium Microbacterium aurum strain B8.A, originally isolated from a potato plant wastewater facility, is able to degrade different types of starch granules. Here we report the characterization of an unusually large, multidomain M. aurum B8.A α-amylase enzyme (MaAmyA). MaAmyA is a 1,417-amino-acid (aa) protein with a predicted molecular mass of 148 kDa. Sequence analysis of MaAmyA showed that its catalytic core is a family GH13_32 α-amylase with the typical ABC domain structure, followed by a fibronectin (FNIII) domain, two carbohydrate binding modules (CBM25), and another three FNIII domains. Recombinant expression and purification yielded an enzyme with the ability to degrade wheat and potato starch granules by introducing pores. Characterization of various truncated mutants of MaAmyA revealed a direct relationship between the presence of CBM25 domains and the ability of MaAmyA to form pores in starch granules, while the FNIII domains most likely function as stable linkers. At the C terminus, MaAmyA carries a 300-aa domain which is uniquely associated with large multidomain amylases; its function remains to be elucidated. We concluded that M. aurum B8.A employs a multidomain enzyme system to initiate degradation of starch granules via pore formation.

Bioproduction of chitooligosaccharides: present and perspectives

Chitin and chitosan oligosaccharides (COS) have been traditionally obtained by chemical digestion with strong acids. In light of the difficulties associated with these traditional production processes, environmentally compatible and reproducible production alternatives are desirable. Unlike chemical digestion, biodegradation of chitin and chitosan by enzymes or microorganisms does not require the use of toxic chemicals or excessive amounts of wastewater. Enzyme preparations with chitinase, chitosanase, and lysozymeare primarily used to hydrolyze chitin and chitosan. Commercial preparations of cellulase, protease, lipase, and pepsin provide another opportunity for oligosaccharide production. In addition to their hydrolytic activities, the transglycosylation activity of chitinolytic enzymes might be exploited for the synthesis of desired chitin oligomers and their derivatives. Chitin deacetylase is also potentially useful for the preparation of oligosaccharides. Recently, direct production of oligosaccharides from chitin and crab shells by a combination of mechanochemical grinding and enzymatic hydrolysis has been reported. Together with these, other emerging technologies such as direct degradation of chitin from crustacean shells and microbial cell walls, enzymatic synthesis of COS from small building blocks, and protein engineering technology for chitin-related enzymes have been discussed as the most significant challenge for industrial application.

Control of chitin and N-acetylglucosamine utilization in Saccharopolyspora erythraea

Chitin degradation and subsequent N-acetylglucosamine (GlcNAc) catabolism is thought to be a common trait of a large majority of actinomycetes. Utilization of aminosugars had been poorly investigated outside the model strain Streptomyces coelicolor A3(2), and we examined here the genetic setting of the erythromycin producer Saccharopolyspora erythraea for GlcNAc and chitin utilization, as well as the transcriptional control thereof. Sacch. erythraea efficiently utilize GlcNAc most likely via the phosphotransferase system (PTS(GlcNAc)); however, this strain is not able to grow when chitin or N,N'-diacetylchitobiose [(GlcNAc)2] is the sole nutrient source, despite a predicted extensive chitinolytic system (chi genes). The inability of Sacch. erythraea to utilize chitin and (GlcNAc)2 is probably because of the loss of genes encoding the DasABC transporter for (GlcNAc)2 import, and genes for intracellular degradation of (GlcNAc)2 by β-N-acetylglucosaminidases. Transcription analyses revealed that in Sacch. erythraea all putative chi and GlcNAc utilization genes are repressed by DasR, whereas in Strep. coelicolor DasR displayed either activating or repressing functions whether it targets genes involved in the polymer degradation or genes for GlcNAc dimer and monomer utilization, respectively. A transcriptomic analysis further showed that GlcNAc not only activates the transcription of GlcNAc catabolism genes but also activates chi gene expression, as opposed to the previously reported GlcNAc-mediated catabolite repression in Strep. coelicolor. Finally, synteny exploration revealed an identical genetic background for chitin utilization in other rare actinomycetes, which suggests that screening procedures that used only the chitin-based protocol for selective isolation of antibiotic-producing actinomycetes could have missed the isolation of many industrially promising strains.

Flavobacterium johnsoniae chitinase ChiA is required for chitin utilization and is secreted by the type IX secretion system

Flavobacterium johnsoniae, a member of phylum Bacteriodetes, is a gliding bacterium that digests insoluble chitin and many other polysaccharides. A novel protein secretion system, the type IX secretion system (T9SS), is required for gliding motility and for chitin utilization. Five potential chitinases were identified by genome analysis. Fjoh_4555 (ChiA), a 168.9-kDa protein with two glycoside hydrolase family 18 (GH18) domains, was targeted for analysis. Disruption of chiA by insertional mutagenesis resulted in cells that failed to digest chitin, and complementation with wild-type chiA on a plasmid restored chitin utilization. Antiserum raised against recombinant ChiA was used to detect the protein and to characterize its secretion by F. johnsoniae. ChiA was secreted in soluble form by wild-type cells but remained cell associated in strains carrying mutations in any of the T9SS genes, gldK, gldL, gldM, gldNO, sprA, sprE, and sprT. Western blot and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses suggested that ChiA was proteolytically processed into two GH18 domain-containing proteins. Proteins secreted by T9SSs typically have conserved carboxy-terminal domains (CTDs) belonging to the TIGRFAM families TIGR04131 and TIGR04183. ChiA does not exhibit strong similarity to these sequences and instead has a novel CTD. Deletion of this CTD resulted in accumulation of ChiA inside cells. Fusion of the ChiA CTD to recombinant mCherry resulted in secretion of mCherry into the medium. The results indicate that ChiA is a soluble extracellular chitinase required for chitin utilization and that it relies on a novel CTD for secretion by the F. johnsoniae T9SS.

Comparative genome analysis of Enterobacter cloacae

The Enterobacter cloacae species includes an extremely diverse group of bacteria that are associated with plants, soil and humans. Publication of the complete genome sequence of the plant growth-promoting endophytic E. cloacae subsp. cloacae ENHKU01 provided an opportunity to perform the first comparative genome analysis between strains of this dynamic species. Examination of the pan-genome of E. cloacae showed that the conserved core genome retains the general physiological and survival genes of the species, while genomic factors in plasmids and variable regions determine the virulence of the human pathogenic E. cloacae strain; additionally, the diversity of fimbriae contributes to variation in colonization and host determination of different E. cloacae strains. Comparative genome analysis further illustrated that E. cloacae strains possess multiple mechanisms for antagonistic action against other microorganisms, which involve the production of siderophores and various antimicrobial compounds, such as bacteriocins, chitinases and antibiotic resistance proteins. The presence of Type VI secretion systems is expected to provide further fitness advantages for E. cloacae in microbial competition, thus allowing it to survive in different environments. Competition assays were performed to support our observations in genomic analysis, where E. cloacae subsp. cloacae ENHKU01 demonstrated antagonistic activities against a wide range of plant pathogenic fungal and bacterial species.

Microdiversity of extracellular enzyme genes among sequenced prokaryotic genomes

Understanding the relationship between prokaryotic traits and phylogeny is important for predicting and modeling ecological processes. Microbial extracellular enzymes have a pivotal role in nutrient cycling and the decomposition of organic matter, yet little is known about the phylogenetic distribution of genes encoding these enzymes. In this study, we analyzed 3058 annotated prokaryotic genomes to determine which taxa have the genetic potential to produce alkaline phosphatase, chitinase and β-N-acetyl-glucosaminidase enzymes. We then evaluated the relationship between the genetic potential for enzyme production and 16S rRNA phylogeny using the consenTRAIT algorithm, which calculated the phylogenetic depth and corresponding 16S rRNA sequence identity of clades of potential enzyme producers. Nearly half (49.2%) of the genomes analyzed were found to be capable of extracellular enzyme production, and these were non-randomly distributed across most prokaryotic phyla. On average, clades of potential enzyme-producing organisms had a maximum phylogenetic depth of 0.008004-0.009780, though individual clades varied broadly in both size and depth. These values correspond to a minimum 16S rRNA sequence identity of 98.04-98.40%. The distribution pattern we found is an indication of microdiversity, the occurrence of ecologically or physiologically distinct populations within phylogenetically related groups. Additionally, we found positive correlations among the genes encoding different extracellular enzymes. Our results suggest that the capacity to produce extracellular enzymes varies at relatively fine-scale phylogenetic resolution. This variation is consistent with other traits that require a small number of genes and provides insight into the relationship between taxonomy and traits that may be useful for predicting ecological function.

Expression and efficient secretion of a functional chitinase from Chromobacterium violaceum in Escherichia coli

BACKGROUND

Chromobacterium violaceum is a free-living β-proteobacterium found in tropical and subtropical regions. The genomic sequencing of C. violaceum ATCC 12472 has revealed many genes that underpin its adaptability to diverse ecosystems. Moreover, C. violaceum genes with potential applications in industry, medicine and agriculture have also been identified, such as those encoding chitinases. However, none of the chitinase genes of the ATCC 12472 strain have been subjected to experimental validation. Chitinases (EC 3.2.1.14) hydrolyze the β-(1,4) linkages in chitin, an abundant biopolymer found in arthropods, mollusks and fungi. These enzymes are of great biotechnological interest as potential biocontrol agents against pests and pathogens. This work aimed to experimentally validate one of the chitinases from C. violaceum.

RESULTS

The open reading frame (ORF) CV2935 of C. violaceum ATCC 12472 encodes a protein (439 residues) that is composed of a signal peptide, a chitin-binding domain, a linker region, and a C-terminal catalytic domain belonging to family 18 of the glycoside hydrolases. The ORF was amplified by PCR and cloned into the expression vector pET303/CT-His. High levels of chitinolytic activity were detected in the cell-free culture supernatant of E. coli BL21(DE3) cells harboring the recombinant plasmid and induced with IPTG. The secreted recombinant protein was purified by affinity chromatography on a chitin matrix and showed an apparent molecular mass of 43.8 kDa, as estimated by denaturing polyacrylamide gel electrophoresis. N-terminal sequencing confirmed the proper removal of the native signal peptide during the secretion of the recombinant product. The enzyme was able to hydrolyze colloidal chitin and the synthetic substrates p-nitrophenyl-β-D-N,N'-diacetylchitobiose and p-nitrophenyl-β-D-N,N',N"-triacetylchitotriose. The optimum pH for its activity was 5.0, and the enzyme retained ~32% of its activity when heated to 60°C for 30 min.

CONCLUSIONS

A C. violaceum chitinase was expressed in E. coli and purified by affinity chromatography on a chitin matrix. The secretion of the recombinant protein into the culture medium was directed by its native signal peptide. The mature enzyme was able to hydrolyze colloidal chitin and synthetic substrates. This newly identified signal peptide is a promising secretion factor that should be further investigated in future studies, aiming to demonstrate its usefulness as an alternative tool for the extracellular production of recombinant proteins in E. coli.

Multiple roles of Asp313 in the refined catalytic cycle of chitin degradation by Vibrio harveyi chitinase A

Three acidic residues in the DXDXE sequence motif are suggested to play a concerted role in the catalysis of Vibrio harveyi ChiA. An increase in the optimum pH of 0.8 units in mutant D313A/N indicates that Asp313 influences the pKa of the ionizing groups around the cleavage site. D313A showed greatly reduced kcat/Km and increased KD, suggesting that Asp313 participates in catalysis and ligand binding. Investigation of the enzyme-substrate interactions of V. harveyi ChiA and Serratia marcescens ChiB revealed two conformations of Asp313 and (-1)GlcNAc. The first conformation, likely to be the initial conformation, showed that the β-COOH of Asp313 only interacted with the -C=O of the N-acetyl group in the distorted sugar. The second conformation, formed from the first by concerted bond rotations, demonstrated hydrogen bonds between the Asp313 side chain and the -NH of the N-acetyl group and the γ-COOH of Glu315. Here we propose a further refinement of the catalytic cycle of chitin hydrolysis by family-18 chitinases that involves four steps: Step 1: Pre-priming. An acidic pair is formed between Asp311 and Asp313. Step 2: Substrate binding. The Asp313 side chain detaches from Asp311 and rotates to form a H-bond with the C=O of the 2-acetamido group of -1GlcNAc. Step 3: Bond cleavage. The side chain of Asp313 and the 2-acetamido group simultaneously rotate, permitting Asp313 to interact with the side chain of Glu315 and facilitating bond cleavage. Step 4: Formation of reaction intermediate. The transient (-1) C1-GlcNAc cation readily reacts with the 2-acetamido group, forming an oxazolinium ion intermediate. Further attack by a neighboring water results in retention of β-configuration of the degradation products.

Crystal structure and mode of action of a class V chitinase from Nicotiana tabacum

A class V chitinase from Nicotiana tabacum (NtChiV) with amino acid sequence similar to that of Serratia marcescens chitinase B (SmChiB) was expressed in E. coli and purified to homogeneity. When N-acetylglucosamine oligosaccharides [(NAG)(n)] were hydrolyzed by the purified NtChiV, the second glycosidic linkage from the non-reducing end was predominantly hydrolyzed in a manner similar to that of SmChiB. NtChiV was shown to hydrolyze partially N-acetylated chitosan non-processively, whereas SmChiB hydrolyzes the same substrate processively. The crystal structure of NtChiV was determined by the single-wavelength anomalous dispersion method at 1.2 Å resolution. The protein adopts a classical (β/α)₈-barrel fold (residues 1-233 and 303-348) with an insertion of a small (α + β) domain (residues 234-302). This is the first crystal structure of a plant class V chitinase. The crystal structure of the inactive mutant NtChiV E115Q complexed with (NAG)₄ was also solved and exhibited a linear conformation of the bound oligosaccharide occupying -2, +1, +2, and +3 subsites. The complex structure corresponds to an initial state of (NAG)₄ binding, which is proposed to be converted into a bent conformation through sliding of the +1, +2, and +3 sugar units to -1, +1, and +2 subsites. Although NtChiV is similar to SmChiB, the chitin-binding domain is present in the C-terminus of the latter, but not in the former. Aromatic amino acid residues found in the substrate binding cleft of SmChiB, including Trp97, are substituted with aliphatic residues in NtChiV. These structural differences appear to be responsible for NtChiV being a non-processive enzyme.

Identification of chitinases Is-chiA and Is-chiB from Isoptericola jiangsuensis CLG and their characterization

A 274-bp conserved fragment of chiA (chiA-CF) was amplified from the genomic DNA of Isoptericola jiangsuensis CLG (DSM 21863, CCTCC AB208287) using the specific PCR primers. Based on chiA-CF sequences, a 5233-bp DNA fragment was obtained by self-formed adaptor PCR. DNA sequencing analysis revealed there were two contiguous open reading frames coding for the precursors of Is-chiA [871 amino acids (aa)] and Is-chiB (561 aa) in the 5233-bp DNA fragment. The Is-chiA and Is-chiB exhibited 58% and 62% identity with ArChiA and ArChiB chitinase from Arthrobacter sp. TAD20, respectively. The Is-chiA and Is-chiB genes were cloned into expression vector pET28a (+) and expressed in Escherichia coli BL21 (DE3) with isopropyl-β-D-thiogalactopyranoside induction. Is-chiA and Is-chiB were 92 kDa and 60 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and showed chitobiosidase and endochitinase activity, respectively. Is-chiA and Is-chiB were purified by Ni-nitrilotriacetic acid affinity chromatography and the characteristics of both Is-chiA and Is-chiB were studied.

Novel features of the polysaccharide-digesting gliding bacterium Flavobacterium johnsoniae as revealed by genome sequence analysis

The 6.10-Mb genome sequence of the aerobic chitin-digesting gliding bacterium Flavobacterium johnsoniae (phylum Bacteroidetes) is presented. F. johnsoniae is a model organism for studies of bacteroidete gliding motility, gene regulation, and biochemistry. The mechanism of F. johnsoniae gliding is novel, and genome analysis confirms that it does not involve well-studied motility organelles, such as flagella or type IV pili. The motility machinery is composed of Gld proteins in the cell envelope that are thought to comprise the "motor" and SprB, which is thought to function as a cell surface adhesin that is propelled by the motor. Analysis of the genome identified genes related to sprB that may encode alternative adhesins used for movement over different surfaces. Comparative genome analysis revealed that some of the gld and spr genes are found in nongliding bacteroidetes and may encode components of a novel protein secretion system. F. johnsoniae digests proteins, and 125 predicted peptidases were identified. F. johnsoniae also digests numerous polysaccharides, and 138 glycoside hydrolases, 9 polysaccharide lyases, and 17 carbohydrate esterases were predicted. The unexpected ability of F. johnsoniae to digest hemicelluloses, such as xylans, mannans, and xyloglucans, was predicted based on the genome analysis and confirmed experimentally. Numerous predicted cell surface proteins related to Bacteroides thetaiotaomicron SusC and SusD, which are likely involved in binding of oligosaccharides and transport across the outer membrane, were also identified. Genes required for synthesis of the novel outer membrane flexirubin pigments were identified by a combination of genome analysis and genetic experiments. Genes predicted to encode components of a multienzyme nonribosomal peptide synthetase were identified, as were novel aspects of gene regulation. The availability of techniques for genetic manipulation allows rapid exploration of the features identified for the polysaccharide-digesting gliding bacteroidete F. johnsoniae.

Molecular properties of the glucosaminidase AcmA from Lactococcus lactis MG1363: mutational and biochemical analyses

The major autolysin AcmA of Lactococcus lactis ssp. cremoris MG1363 is a modular protein consisting of an N-terminal signal sequence, a central enzymatic region (glu(acma) as a glucosaminidase), and a C-terminal cell-recognition domain (LysM123). glu(acma) (about 160 amino acids) belongs to the glycoside hydrolase (GH) 73 family, and the two acidic residues E128 and D153 have been thought to be catalytically important. In this study, amino-acid substitution analysis of AcmA was first carried out in the Escherichia coli system. Point mutations E94A, E94Q, E128A, D153A, and Y191A markedly reduced cell-lytic activity (3.8%, 1.1%, 4.2%, 4.8%, and 2.4%, respectively), whereas E128Q and D153N retained significant residual activities (32.1% and 44.0%, respectively). On the other hand, Y191F and Y191W mutations retained high activities (66.2% and 46.0%, respectively). These results showed that E94 (rather than E128 and D153) and the aromatic residue Y191 probably play important roles in catalysis of AcmA. Together with mutational analysis of another GH73 glucoaminidase Glu(atlwm) from the Staphylococcus warneri M autolysin Atl(WM), these results suggested that the GH73 members cleave a glycosidic bond via a substrate-assisted mechanism, as postulated in the GH20 members. AcmA and Glu(atlwm) were purified from E. coli recombinant cells, and their enzymatic properties were studied.

Substrate binding modes and anomer selectivity of chitinase A from Vibrio harveyi

High-performance liquid chromatography mass spectrometry (HPLC MS) was employed to assess the binding behaviors of various substrates to Vibrio harveyi chitinase A. Quantitative analysis revealed that hexaNAG preferred subsites −2 to +2 over subsites −3 to +2 and pentaNAG only required subsites −2 to +2, while subsites −4 to +2 were not used at all by both substrates. The results suggested that binding of the chitooligosaccharides to the enzyme essentially occurred in compulsory fashion. The symmetrical binding mode (−2 to +2) was favored presumably to allow the natural form of sugars to be utilized effectively. Crystalline α chitin was initially hydrolyzed into a diverse ensemble of chitin oligomers, providing a clear sign of random attacks that took place within chitin chains. However, the progressive degradation was shown to occur in greater extent at later time to complete hydrolysis. The effect of the reducing-end residues were also investigated by means of HPLC MS. Substitutions of Trp275 to Gly and Trp397 to Phe significantly shifted the anomer selectivity of the enzyme toward β substrates. The Trp275 mutation modulated the kinetic property of the enzyme by decreasing the catalytic constant (k_cat) and the substrate specificity (k_cat/K_m) toward all substrates by five- to tenfold. In contrast, the Trp397 mutation weakened the binding strength at subsite (+2), thereby speeding up the rate of the enzymatic cleavage toward soluble substrates but slowing down the rate of the progressive degradation toward insoluble chitin.

Cloning and expression of a chitinase gene from Sanguibacter sp. C4

The chitinase Chi58 is an extracellular chitinase produced by Sanguibacter sp.strain C4. The gene-specific PCR primers were used to detect the presence of the chiA gene in strain C4. A chiA fragment (chiA-F) was amplified from the C4 genomic DNA and was used to blast-search the related sequences from the GenBank database. By alignment and selection of the highly conserved regions of the homologous sequences, two pairs of primers were designed to amplify the open reading frame (ORF) of the chitinase from strain C4 by nested PCR. The results revealed that the Chi58 ORF consisted of 1 692 nucleotides encoding a protein of 563 amino acid residues. The molecular weight of the mature protein was predicted to be 58.544 kDa. The Chi58 ORF was a modular enzyme composed of a signal peptide sequence, a polycystic kidney disease I domain, and a glycosyl hydrolase family 18 domain. The chitinase of C4 exhibited a high level of similarity to the chitinase A of Serratia (88.9%-99.6%) at the amino acid sequence level. The Chi58 gene was cloned into the expression vector pET32a to construct the recombinant plasmid pChi58 and was expressed in E. coli BL-21 (DE3) cells with IPTG induction. The molecular weight of the Trx-Chi58 fusion protein was estimated to be 81.1 kDa by SDS-PAGE.

Characterization of antifungal chitinase from marine Streptomyces sp. DA11 associated with South China Sea sponge Craniella australiensis

The gene cloning, purification, properties, kinetics, and antifungal activity of chitinase from marine Streptomyces sp. DA11 associated with South China sponge Craniella australiensis were investigated. Alignment analysis of the amino acid sequence deduced from the cloned conserved 451 bp DNA sequence shows the chitinase belongs to ChiC type with 80% similarity to chitinase C precursor from Streptomyces peucetius. Through purification by 80% ammonium sulfate, affinity binding to chitin and diethylaminoethyl-cellulose anion-exchange chromatography, 6.15-fold total purification with a specific activity of 2.95 Umg(-1) was achieved. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed a molecular weight of approximately 34 kDa and antifungal activities were observed against Aspergillus niger and Candida albicans. The optimal pH, temperature, and salinity for chitinase activity were 8.0, 50 degrees C, and 45 g per thousand psu, respectively, which may contribute to special application of this marine microbe-derived chitinase compared with terrestrial chitinases. The chitinase activity was increased by Mn(2+), Cu(2+), and Mg(2+), while strongly inhibited by Fe(2+) and Ba(2+). Meanwhile, SDS, ethyleneglycoltetraacetic acid, urea, and ethylenediaminetetraacetic acid were found to have significantly inhibitory effect on chitinase activity. With colloidal chitin as substrates instead of powder chitin, higher V (max) (0.82 mg product/min.mg protein) and lower K (m) (0.019 mg/ml) values were achieved. The sponge's microbial symbiont with chitinase activity may contribute to chitin degradation and antifungal defense. To our knowledge, it was the first time to study sponge-associated microbial chitinase.

A novel goose-type lysozyme gene with chitinolytic activity from the moderately thermophilic bacterium Ralstonia sp. A-471: cloning, sequencing, and expression

In this study, we cloned the gene encoding goose-type (G-type) lysozyme with chitinase (Ra-ChiC) activity from Ralstonia sp. A-471 genomic DNA library. This is the first report of another type of chitinase after the previously reported chitinases ChiA (Ra-ChiA) and ChiB (Ra-ChiB) in the chitinase system of the moderately thermophilic bacterium, Ralstonia sp. A-471 and also the first such data in Ralstonia sp. G-type lysozyme gene. It consisted of 753 bp nucleotides, which encodes 251 amino acids including a putative signal peptide. This ORF was modular enzyme composed of a signal sequence, chitin-binding domain, linker, and catalytic domain. The catalytic domain of Ra-ChiC showed homologies to those of G-type lysozyme (glycoside hydrolases (GH) family 23, 16.8%) and lysozyme-like enzyme from Clostridium beijerincki (76.1%). Ra-ChiC had activities against ethylene glycol chitin, carboxyl methyl chitin, and soluble chitin but not against the cell wall of Micrococcus lysodeikticus. The enzyme produced alpha-anomer by hydrolyzing beta-1,4-glycosidic linkage of the substrate, indicating that the enzyme catalyzes the hydrolysis through an inverting mechanism. When N-acetylglucosamine hexasaccharide [(GlcNAc)6] was hydrolyzed by the enzyme, the second and third glycosidic linkage from the non-reducing end were split producing (GlcNAc)2 + (GlcNAc)4 and (GlcNAc)3 + (GlcNAc)3 of almost the same concentration in the early stage of the reaction. The G-type lysozyme hydrolyzed (GlcNAc)6 in an endo-splitting manner, which produced (GlcNAc)3 + (GlcNAc)3 predominating over that to (GlcNAc)2 + (GlcNAc)4. Thus, Ra-ChiC was found to be a novel enzyme in its structural and functional properties.

Identification and characterization of genes underlying chitinolysis in Collimonas fungivorans Ter331

Through a combinatorial approach of plasposon mutagenesis, genome mining, and heterologous expression, we identified genes contributing to the chitinolytic phenotype of bacterium Collimonas fungivorans Ter331. One of five mutants with abolished ability to hydrolyze colloidal chitin carried its plasposon in the chiI gene coding for an extracellular endochitinase. Two mutants were affected in the promoter of chiP-II coding for an outer-membrane transporter of chitooligosaccharides. The remaining two mutations were linked to chitobiose/N-acetylglucosamine uptake. Thus, our model for the Collimonas chitinolytic system assumes a positive feedback regulation of chitinase activity by chitin degradation products. A second chitinase gene, chiII, coded for an exochitinase that preferentially released chitobiose from chitin analogs. Genes hexI and hexII showed coding resemblance to N-acetylglucosaminidases, and the activity of purified HexI protein towards chitin analogs suggested its role in converting chitobiose to N-acetylglucosamine. The hexI gene clustered with chiI, chiII, and chiP-II in one locus, while chitobiose/N-acetylglucosamine uptake genes colocalized in another. Both loci contained genes for conversion of N-acetylglucosamine to fructose-6-phosphate, confirming that C. fungivorans Ter331 features a complete chitin pathway. No link could be established between chitinolysis and antifungal activity of C. fungivorans Ter331, suggesting that the bacterium's reported antagonism towards fungi relies on other mechanisms.

Chitin hydrolysis by Listeria spp., including L. monocytogenes

Listeria spp., including the food-borne pathogen Listeria monocytogenes, are ubiquitous microorganisms in the environment and thus are difficult to exclude from food processing plants. The factors that contribute to their multiplication and survival in nature are not well understood, but the ability to catabolize various carbohydrates is likely to be very important. One major source of carbon and nitrogen in nature is chitin, an insoluble linear beta-1,4-linked polymer of N-acetylglucosamine (GlcNAc). Chitin is found in cell walls of fungi and certain algae, in the cuticles of arthropods, and in shells and radulae of molluscs. In the present study, we demonstrated that L. monocytogenes and other Listeria spp. are able to hydrolyze alpha-chitin. The chitinolytic activity is repressed by the presence of glucose in the medium, suggesting that chitinolytic activity is subjected to catabolite repression. Activity is also regulated by temperature and is higher at 30 degrees C than at 37 degrees C. In L. monocytogenes EGD, chitin hydrolysis depends on genes encoding two chitinases, lmo0105 (chiB) and lmo1883 (chiA), but not on a gene encoding a putative chitin binding protein (lmo2467). The chiB and chiA genes are phylogenetically related to various well-characterized chitinases. The potential biological implications of chitinolytic activity of Listeria are discussed.

Biochemical characteristics of C-terminal region of recombinant chitinase from Bacillus licheniformis: implication of necessity for enzyme properties

The functional and structural significance of the C-terminal region of Bacillus licheniformis chitinase was explored using C-terminal truncation mutagenesis. Comparative studies between full-length and truncated mutant molecules included initial rate kinetics, fluorescence and CD spectrometric properties, substrate binding and hydrolysis abilities, thermostability, and thermodenaturation kinetics. Kinetic analyses revealed that the overall catalytic efficiency, k(cat)/K(m), was slightly increased for the truncated enzymes toward the soluble 4-methylumbelliferyl-N-N'-diacetyl chitobiose or 4-methylumbelliferyl-N-N''-N'''-triacetyl chitotriose or insoluble alpha-chitin substrate. By contrast, changes to substrate affinity, K(m), and turnover rate, k(cat), varied considerably for both types of chitin substrates between the full-length and truncated enzymes. Both truncated enzymes exhibited significantly higher thermostabilities than the full-length enzyme. The truncated mutants retained similar substrate-binding specificities and abilities against the insoluble substrate but only had approximately 75% of the hydrolyzing efficiency of the full-length chitinase molecule. Fluorescence spectroscopy indicated that both C-terminal deletion mutants retained an active folding conformation similar to the full-length enzyme. However, a CD melting unfolding study was able to distinguish between the full-length and truncated mutant molecules by the two phases of apparent transition temperatures in the mutants. These results indicate that up to 145 amino acid residues, including the putative C-terminal chitin-binding region and the fibronectin (III) motif of B. licheniformis chitinase, could be removed without causing a seriously aberrant change in structure and a dramatic decrease in insoluble chitin hydrolysis. The results of the present study provide evidence demonstrating that the binding and hydrolyzing of insoluble chitin substrate for B. licheniformis chitinase was not dependent solely on the putative C-terminal chitin-binding region and the fibronectin (III) motif.

Molecular analysis of the gene encoding a new chitinase from the marine psychrophilic bacterium Moritella marina and biochemical characterization of the recombinant enzyme

The marine psychrophilic bacterium Moritella marina, isolated from a sample raised from a depth of 1,200 m in the northern Pacific Ocean, secretes several chitinases in response to chitin induction. A gene coding for an extracellular chitinolytic enzyme was cloned and its nucleotide sequence was determined. The chitinase gene consists of an open reading frame of 1,650 nucleotides and encodes a protein of 550 amino acids with a calculated molecular weight of 60.788 kDa, named MmChi60. MmChi60 has a modular structure consisting of a glycosyl-hydrolase family 18 N-terminal catalytic region as well as a C-terminal chitin-binding domain (ChBD). The new chitinase was purified to homogeneity from the intracellular fraction of Escherichia coli. The optimum pH and temperature of the recombinant MmChi60 were 5.0 and 28 degrees C, respectively. The mode of action of the new enzyme on N-acetylchitooligomers, chitin polymers, and other substrates was examined, and MmChi60 was classified as an endochitinase. Thermal unfolding of MmChi60 was studied using differential scanning microcalorimetry and revealed that the protein unfolds reversibly at 65 degrees C. On the basis of the crystal structure of the chitinase C of Streptomyces griseus, a homology-based 3-D model of the ChBD of the MmChi60 was calculated.

Serum YKL-40 levels and chitotriosidase activity as potential biomarkers in primary prostate cancer and benign prostatic hyperplasia

BACKGROUND

YKL-40, also called human cartilage glycoprotein-39 (HC gp-39) and chitotriosidase are homologs of family 18 glycosyl hydrolases secreted by human macrophages. Although high levels of YKL-40 and chitotriosidase are associated with several diseases, the physiological functions of these enzymes are still unclear. YKL-40, a growth factor for connective tissue cells, a migration factor for endothelial and vascular smooth muscle cells, is expressed by several types of solid human carcinoma, including prostate carcinoma.

PURPOSE

The purpose of this study was to compare serum YKL-40 levels and chitotriosidase activity both in benign prostatic hyperplasia and primary prostate cancer.

METHODS

YKL-40 and chitotriosidase were determined in serum samples from 93 patients with primary prostate cancer and 61 patients with benign prostatic hyperplasia. Serum YKL-40 levels were measured by ELISA and chitotriosidase activity was determined by fluorometer. PSA levels were also measured by using an automated system.

RESULTS

Serum YKL-40 levels were significantly higher (P < 0.001) in patients with prostate cancer compared with control group whereas there was no significant difference between BPH and control group. Serum chitotriosidase activities were significantly higher in carcinoma patients with high Gleason score than the control group (P < 0.001). No significant difference was observed in BPH patients (P > 0.05). Both YKL-40 and chitotriosidase were found statistically significant higher in primary prostate cancer and BPH.

CONCLUSION

High serum YKL-40 levels in patients with primary prostate cancer indicate that YKL-40 may have a function in the progression of malignant diseases, whereas no significant elevation was observed in benign prostatic hyperplasia. Meanwhile, high serum chitotriosidase activity was observed only in patients with Gleason high grade, indicating possible macrophage involvement in cancer progression. Further studies are needed to elucidate the biologic role of YKL-40 in cancer aggressiveness and in progression of malignant diseases.