3.1 Metagenome analysis
Metagenome, having accession number SRR14690790, for Mycobacterium tuberculosis was downloaded from SRA database.
As, per Per base sequence quality results (Fig. 1) of FASTQC and MultiQC, the sequence quality is not good hence we go ahead with trimming the sequence.
CUTADAPT tool [27] is used for trimming. It finds and removes adapter sequences, primers, poly-A tails, and other types of unwanted sequence from our data. It searches for the adapter in all reads and removes it when it finds it. Further, sequence quality of the cutadapt output is checked using FASTQC and MultiQC and it is found within the range.
SortMeRNA tool removes any reads identified as rRNA from our dataset. Fastq Interlace tool joins paired end FASTQ reads from two separate files. Taxonomic profiling [28] was done using MetaPhlAn tool (Fig. 2). The output is visualized using Krona and Graphlan (Table 1, Fig. 3).
After generation of taxonomy, we move to functional information of our microbiome. Functional information of the above microbiome community [28] was done using HUMAnN pipeline.
Table 1
Normalized gene families
# Gene Family
|
humann_Abundance-RELAB
|
UNMAPPED
|
0.999872
|
UniRef90_X8FHU5
|
0.000116922
|
UniRef90_X8FHU5|unclassified
|
0.000116922
|
UniRef90_Z9JRB3
|
1.08765e-05
|
UniRef90_Z9JRB3|unclassified
|
1.08765e-05
|
Next, from the gene family information, we obtain the functional information of our microbiome using Superfamily server. The Functional information of 1st five families from Normalized gene families as detected by Superfamily (HMM library and genome assignments server) is given in table 2 & 3 below.


Relationships were determined –
By using this factor we selected the specific bacteriophage (Mycobacteriophage lysine B D29 gp12). It is determined by global alignment tool from NCBI (Table 4, Fig. 4).
Global alignment result:
Needleman-Wunsch algorithm
Source-https://blast.ncbi.nlm.nih.gov
Table 4
SL.NO
|
ORGANISMS
|
ACCESSION NO
|
1.
|
Mycobacteriophage D29 DNA coat protein
|
X70353.1
|
2.
|
Mycobacterium tuberculosis H37Rv
|
KY702779.1
|
3.2-Structure based Drug designing of Mycobacterium tuberculosis-
Since, Tuberculosis is bacterial disease; we further go ahead towards designing novel drug for the disease. From the MetaPhlAn: Bowtie2 output we get the gene ids. Corresponding gene receptors (macromolecules) are taken from NCBI for our work (Table 5).
Table 5
Genes with their NCBI Accession number
Sl. No
|
Gene Receptors
|
Number NCBI Accession
|
Homologous Template
|
1.
|
CR3
|
QRN45544.1
|
3K6SB
|
2
|
Dectin 1
|
AAH71746.1
|
1MPUA
|
3
|
IRAK4
|
NP_001338274.1
|
5UIUA
|
4
|
CXCL8
|
NP_001341769.1
|
6N2UA
|
Abbreviations of genes:
1. CR3 - Complementary Receptor
2. CLEC7A - C-type lectin domain family 7, member A
3.CXCL8 - C-X-C Motif chemokine ligand 8
4.IRAK4 - Interleukin 1 Receptor Associated kinase 4
Homology modeling
Homology modeling of the above receptors are done using SWISS-MODEL server. The receptor model and corresponding ramachandran plot results are given in Fig. 5. Template used for modeling is given in Table-5.
Table 6
Proteins with their NCBI Accession number
SL.NO
|
PROTEINS
|
ACCESSION NUMBER
|
HOMOLOGOUS TEMPLATE
|
1.
|
Eis
|
AVV29810.1
|
5EBV.1.F
|
2.
|
Erm37
|
KBG11004.1
|
6NVM.1.A
|
3.
|
Inh A
|
AVV29586.1
|
2PR.2.A
|
4.
|
kasB
|
CCE37716.1
|
2GP.6.A
|
5.
|
Mar A
|
OMH59859.1
|
3W6V.1.A
|
6.
|
Rpob
|
AEJ88322.1
|
6VW.0.1.C
|
7.
|
TlyA
|
CCP44459.1
|
5KS.2.1.A
|
8.
|
WhiB7
|
AJF05229.1
|
7KIM.1.K
|
Abbreviations of proteins:
1. Eis - Enhanced intracellular survival
2. Erm37 - Expression resistant macrolide
3. InhA - Inhibin alpha
4. KasB - Beta keto acyl carrier protein
5. Mar A -Multiple antibiotic Resistant
6. Rpob -Rifampin resistant gene (Beta subunit of bacterial RNA polymerase)
7. Tly A -Cytidine methyl transferase A.
8. WhiB7 - Probable transcription regulator
Homology modeling-
Homology modeling of the above receptors (micromolecules) are done using SWISS-MODEL server. The receptor model and corresponding ramachandran plot results are given in Fig. 6. Template used for modeling is given in Table 6.
Bacteriophage exhibit catalytic mechanism on binding with various proteins or carbohydrates motif. This study of phage-host interaction can inform small molecule drug discovery by revealing new drug targets and pinpointing their weakness. Mycobacteriophage lysine B D29 can hydolysed the mycolylarabinogalactan bonds and inactivates antibiotic resistant proteins (Table 7). The potential activity of Mycobacteriophage lysine B D29 against antibiotic resistant protein of Mycobacterium tuberculosis is studied here.
Table-7
Docking scores and RMSD value of Mycobacteriophage B D29 lysin with bacterial proteins
SL.NO
|
TEMPLATE.NO
|
PROTEINS
|
LIGANDS
|
DOCKING SCORE
Kcal/mol
|
RMSD Value
Angstrom
|
1.
|
2PR2.1.A
|
Inh A
|
Phage lysine B D29
|
-16652
|
4
|
2.
|
2GP6.1.A
|
Kas B
|
Phage lysine B D29
|
-16012
|
4
|
3.
|
5EBV.1.F
|
Eis
|
Phage lysine B D29
|
-19224
|
4
|
4.
|
7KIM.1.K
|
WhiB7
|
Phage lysine B D29
|
-13710
|
4
|
5.
|
6VW0.1.C
|
Rpob
|
Phage lysine B D29
|
-18264
|
4
|
6.
|
6NVM.1.A
|
Erm37
|
Phage lysin B D29
|
-13614
|
4
|
7.
|
5KS2.1.A
|
TlyA
|
Phage lysine B D29
|
-13792
|
4
|
8.
|
3W6V.1.A
|
Mar A
|
Phage lysine B D29
|
-12638
|
4
|
It is seen that Mycobacteriophage lysine B D29 has good docking scores with MarA (multidrug antibiotic resistant proteins), Erm37, whiB7. Patch dock server used to dock the proteins (Table 8). Protein protein model interaction analysed. Gromacs minimization energy by Galaxy Europe server and structural charges , aminoacids identification were performed using Vienna-ptm server.
Further docking is performed with the receptors in Table 6 with the Mycobacteriophage B lysine D29.
Table 8
Docking scores and RMSD value of Human receptors with bacterial proteins.
SL.
NO
|
RECEPTOS
|
LIGAND-
1
|
LIGAND-
2
|
DS-1
Kcal/mol
|
DS-2
Kcal/mol
|
RMSD value angst-rom
|
1.
|
CR3
|
Eis
|
InhA
|
-14726
|
-14260
|
4
|
2.
|
DECTIN
|
WhiB7
|
Rpob
|
-12610
|
-17644
|
4
|
3.
|
IRAK4
|
KasB
|
Erm37
|
-16198
|
-15514
|
4
|
4.
|
CXCL8
|
TlyA
|
MarA
|
-14418
|
-15096
|
4
|
Dectin 1 receptor with WhiB7 bacterial proteins (Transciptional regulators) has good docking scores. It exhibit good binding sites.
To select the putative site, an analogous experiment was performed with the bacteriophage protein and the sites were compared. The lysine B bacteriophage D29 had close overlap with Mar A gene binding sites and the binding energies were comparable (delta G bind=-12638 kcal/mol). Final verification of docking experiments performed with MD simulation which suggested stable binding sites. To help understand discrimination of different proteins in site 2, the docking of both protein protein was performed with a high precision Vienna-ptm server.
Molecular dynamics simulation of antibiotic resistant bacterial protein is selected sites for binding Mycobacteriophage lysine B D29 gp12 protein. MD simulation was performed in 150mM water at 300k for 100 ns (Table 8).
As per docking results and verification by molecular dynamics simulation it was found that the whib7 protein has good affinity in binding with Mycobacteriophage D29 lysin B. It depicts that Mycobacteriophage D29 Lysin B plays an important role at transcription process, it stop the transcription process of whib7 and do not allow the production of antibiotic resistant protein. Here we also characterize insilico the predicted interaction of gene protein 12 from Mycobacteriophage D29 with Mycobacterium tuberculosis antibiotic resistant protein (TlyA), Multidrug resistant protein(Mar A), Rifampin resistant protein(rpob), expression resistant macrolide (Erm 37). All these proteins plays an important role in the transcription process in bacterial cells and has been proposed (Table 9, Fig. 7).