Category:Team North Phace

PBSX is a late operon that consists of a gene that codes for a putative holin. Figure 2 of the article shows that the turbidity of the bacteria (at 550 nm) in the L8508 and POP1234 cultures decreased after the induction of PBSX, which contributes to the evidence for holin's function as lysis.

Figure 6, contains a graph measuring the OD550 (optical density) over time (hours). The lines on the graph showed various lysis genes. These genes had a combination of mutant strains of xhylA (encodes for putative endolysin), xhlB (encodes for putative holin), or xlyA inject inside of them. According to the graph the lines with with solid triangles (POP1234), solid squares (SK109), and a hallow square (SK110) all decreased in turbidity. Since three of these cultures contained contained strains of either xlyA or xhlB; indicating the bacteria in the culture died due to lysis. This proves holin and endolysin play a major role in lysis.

Figure 2, plots a graph with A550 on the y axis and time of induction (min) on the x axis. The graph illustrated how the alleles tQ87am and tQ209am contain partial Holin activity. When the two alleles are present in the sample; the turbidity decrease indicating the bacteria has died, due to lysis activity. The alleles tQ87am and tQ209am supports gradual lysis after 40 min and 75 min, respectively.

Figure 2 shows the microscopic images of the bacterial cells pre and post induction of the Lambda lysis genes. Before the induction of the lysis genes, there was an abundant amount of bacterial cells present. After 25 minutes of the induction of the Lambda lysis genes, the amount of bacterial cells significantly decreased, showing that the cells were broken apart and lysed.

Figure 5 shows a line (A) and histogram(B) that plots the peptidoglycan degradation in Ecoli in response to the introduction of SPN1S endolysin into the sample. The endolysin seems to cleave the glycosydic linkage between the peptidoglycan molecules to reduce the overall optical density.

Holin Annotation Notes:

Hol 118(83) is a naturally occurring altered portion of the Holin gene “Hol118” which affects cell lysis timings. Hol118(83) had a truncated N-Terminal (Thus a different start codon then usual) and when translated this portion showed slowed cell lysis. The figure shows decrease in optical density for the Hol118(83) mutant phenotypes. The mutant phenotypes were replaced with different start codons which allowed for an increase rate of cell lysis as compared with the wild type Hol118(83). The actual function of Hol118 in the holin polypeptide chain is to increase the rate of cell lysis so by induction the portion of the N-terminal that was missing in the Hol118(83) seemed to counteract its effects and allow for normal functioning .In conclusion Hol118(83) was a strong antiholin that was already present in the holin genome which could be why in UniProt we see both Holin and Antiholin functions.

Figure 4 shows a SDS-Page analysis of the two gp24.1 and gp 26. The bands for gp 24.1 are shown under the Membrane section of the plate signifying that this gene is a membrane localized gene.