MLPs are more numerous in comparison with DLPs
Out of the 5,569 pathogen proteins from 630 pathogens, a total of 5,255
proteins from 612 pathogens were involved in mimicry of the host
interactor proteins using similar domains or motifs. The DLPs in the
entire database were found to be 2,06,449 whereas the MLPs were found to
38,45,643. The number of DLPs and MLPs for each pathogen category are
listed in Table 1. Viruses showed the highest number of DLPs and MLPs,
likely to be due to the preponderance of virus HP-PPIs in the data.
Interestingly, of the total 61,215 HP-PPIs reported, only 1,549 were
found to be characterized by domain mimicry whereas 49,266 were found to
characterized by mimicked motifs. The total number of HP-PPIs, the
fraction of HP-PPIs characterized by mimicked domains and by motifs were
compared pathogen categories and are shown in Figure 3. Motif mimicry
dominates in number over domain mimicry across the known HP-PPIs across
all pathogen categories. Interestingly, as evident from Table 1, a large
number of DLPs were also found in viruses (1,14,899), but were
concentrated in only 822 HP-PPIs (or 1.7%) of the entire viral
interactome as depicted in Figure 3. Conversely, in case of Fungi, very
few HP-PPIs have been reported but still a large proportion of them were
found to be characterized by mimicked candidates. Previous studies have
reported the extensive use of motif mimicry by viral proteomes (25,
52-54). A reason for this monopoly can be that viruses being obligately
intra cellular, incapable of synthesizing the DNA or RNA (25), and
having a rapidly evolving genome need to hijack the major host processes
which includes various metabolic and cellular signalling pathways. Our
data indicates that molecular mimicry may be comparatively much more
frequent in case of fungi. However, our results about frequency should
be treated with caution as the mapping of the host pathogen interactome
is far from complete.