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Comment
. 2019 Sep 11;5(9):eaay5611.
doi: 10.1126/sciadv.aay5611. eCollection 2019 Sep.

Response to Comment on "A commensal strain of Staphylococcus epidermidis protects against skin neoplasia" by Nakatsuji et al

Teruaki Nakatsuji  1 , William Fenical  2 , Richard L Gallo  1
Affiliations
Comment

Response to Comment on "A commensal strain of Staphylococcus epidermidis protects against skin neoplasia" by Nakatsuji et al

Teruaki Nakatsuji et al. Sci Adv. .

Abstract

Kozmin et al. contend that observations previously reported regarding the antimicrobial and antitumor activities of 6-N-hydroxy aminopurine (6-HAP) were incorrect. Their conclusions rely on poorly characterized reagents and focus strictly on in vitro techniques without validation in relevant mammalian model systems. We are pleased to be able to illuminate the weaknesses in their technical comment. The totality of current results continues to support our original conclusion that a strain of the common human commensal skin bacterium, Staphylococcus epidermidis, produces 6-HAP that can inhibit tumor growth.

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Figures

Fig. 1
Fig. 1. Molecular weight of 6-HAP-MPB on the package label does not correspond to that of 6-HAP.
(Photo credit: Teru Nakatsuji, University of California, San Diego.)
Fig. 2
Fig. 2. 6-HAP-MPB does not contain a chemical that is identical to 6-HAP.
(A) 6-HAP-MPB was dissolved in 99% acetonitrile/1% TFA (trifluoroacetic acid) and subjected to high-resolution ESI-TOF-MS. Peaks were scanned between m/z 100 and 1250 in positive ion mode. (B) Estimated chemical composition of three major peaks detected in 6-HAP-MPB. None of them correspond to that of 6-HAP (theoretical mass, 151.0489).
Fig. 3
Fig. 3. 6-HAP has antimicrobial activity, but 6-HAP-MPB does not.
Antimicrobial activity of indicated concentration of 6-HAP or 6-HAP-MPB was measured against group A Streptococcus (NZ131) with a radial diffusion assay. Black circle of zone of growth inhibition represents antimicrobial activity of 6-HAP (arrows). The method of this assay has been provided in our original manuscript.
Fig. 4
Fig. 4. 6-HAP can be spontaneously deoxidized in solution within 24 hours.
(A and B) Native 6-HAP was dissolved in heated H2O (60°C) at 0.1 mg/ml and incubated at room temperature for 24 hours. Degradation of 6-HAP was characterized by low-resolution ESI-TOF-MS (A), followed by the high-resolution mode (B). All 6-HAP was degraded after a 24-hour incubation. (C) Estimated chemical composition of two major peaks detected in (B).
See this image and copyright information in PMC

Comment on

References

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